# Resistor 15k A thermistor is a thermometer that is made of semiconductor that its resistance value changes with temperature. Thermistor will has resistor 15k own temperature coefficient rating which tells us the amount of resistance changed or involved for every Kelvin or Celcius changes. There are two types of thermistor, the Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC).

With an NTC thermistor, when the temperature increases, its resistance decreases. This type of thermistor is widely used. On the contrary, A PTC thermistor will works the other way round, when temperature increases, its resistance will also increase. This type of thermistor is generally used as a fuse. Thermistor resistance change is not in linear throughout the wide range of temperature. Thus some manufacturer will state all the temperature coefficient values as a table for whole or wide range of temperature OR provide only one coefficient value which is valid within a short range of temperature measurement (example -20 to 105 degree C).

We need to convert the resistance value measurement to voltage input value which is within 0 to 5V so that it is measurable by Arduino Analog Pin. In Arduino UNO board, there are 6 Analog Pins (A0 – A5) available for NTC thermistor temperature measurement.

Since the thermistor sensor acts as a resistor, the 2-wire sensor does not have polarity, you can connect any pin to Analog Pin and another one to the Ground Pin. However, in order to convert from resistance to voltage, the Voltage Divider Method is used.

The voltage divider consists of two resistors connected in series as shown in the diagram below. All you need is just 2 resistors with different resistance values, and a 5V voltage supply.

The resistance can be resistor 15k calculate since analog value can be read by Arduino. You can put any R1 and R2 resistor values but recommend to stay below 50k ohm resistor 15k total. In this example, we put R1 as 10k ohm resistor and R2 will be the rating of the thermistor which we choose 5k ohm rating at 25 degree C.

R2 value is the value that will keep changing. By applied the formula above, the analog resistor 15k can be converted to the resistance value which is needed to substitute in the second part of our calculation, the thermistor equation. Choosing a Thermistor temperature sensor When you buy a NTC thermistor, there are 3 important information that need to know.

1) Resistance value As stated earlier, the resistance of an NTC thermistor is changing depending on temperature. However, in order to rate a thermistor, the standard temperature that most manufacturers use is the 25 degree Celsius which is equivalent to room temperature. So the most common and market available resistance value for thermistor temperature sensor is 5k ohm, 10k ohm, 50k ohm, 100k ohm and even 200k ohm at 25 degree. I prefer getting a low resistance value thermistor. 2) Beta or B value (Temperature coefficient) The beta value or B value is the temperature gradient value which defines the resistance changed in two different temperature points or limit (T1 and T2). The based temperature point T1, which is usually 25 degree Celcius (298.15K) and T2 is usually refers to the measurement temperature limit, example 100 degree Celcius (373.15K).

The B value resistor 15k in B T1/T2 form will be B 25/100 and should be within 3000 to 5000. So if measurement temperature is within this range, the B value is applicable while beyond the measurement range the B value might be slightly changed because in wider temperature range the temperature gradient is not linear. 3) Head type of the thermistor There are a lot of shapes and sizes of thermistor. What we are looking at is the silver head sensor with an extension cable of about 15cm to 1m as the first picture above.

The head can be round, rectangle or looks like cable lug shape to suit your application needs. Thermistor Equation The first part of calculation was getting the resistance value R2 which is converted from the resistor 15k reading from the thermistor. This is the second part of calculation where the resistance value R2 is then substitute to Thermistor Equation to obtain its temperature value T2. We are using thermistor equation as below: Not to confuse with the R1 & R2 value on previous calculation which is based on voltage divider method.

All the values in thermistor equation are referring to the thermistor itself. The value R1 and T1 refer to the thermistor standard rating (resistance at 25 degree celcius) while R2 is value from previous calculation and the T2 is the actual temperature that we need to find. There is no exam over here and you do not need to memorize it. We know that the formula is a bit complicated but the purpose of resistor 15k it to you is just to let you know that we are using the above formula for calculation, nothing more.

Hardware Connection Once you get the temperature sensor and resistor ready, you may start to do hardware wiring. Below is the schematic of the wiring. I recommend you to get a mini breadboard to put it next to the Arduino to put your resistor and wiring which is available here !!! Arduino with NTC Thermistor Wiring Diagram Software Codes The final step would be adding source code onto Arduino board. I assume you have installed the Arduino Software.

Resistor 15k are two source code files attached, the first source code is normal NTC temperature code for people out there without the LCD Display. The measured temperature value can be shown in Serial Monitor using Arduino Software.

The second one is the NTC temperature code with LCD display shield function. Once the code is uploaded to the Arduino board, the temperature value resistor 15k be shown on the LCD Display. I recommend you to add a 16X2 LCD Display Shield which can be directly fit on to the top of the Arduino board without the need of extra wiring for the LCD Display. Without the LCD Display, you can only monitor the measured current value on PC via Serial Monitor.

You can get the LCD Display board at our affiliate link here!!!. Datalogger Shield If you plan to record the data in a proper way, you may consider this Datalogger Shield. It allows your arduino to record your data in SD Card. Datalogger shield is often installed together with LCD Display shield. Please find it at our affiliate link here !!! For more about this Datalogger Shield, kindly visit our post here.

Screw Shield / Expansion Shield When there are a lot of wiring around especially more than 1 sensor, sharing pins will be difficult as existing pins (ground and 5V) are limited. This shield provides a lot of convenient terminals for each of the input and output pins. The shield can be mounted directly on top of the Arduino Uno board or in between the shields which made it very convenient to use.

Ohm's Law shows the relationship between voltage, current and resistance To make a current flow through a resistance there must be a voltage across that resistance.

Ohm's Law shows the relationship between the three quantities: voltage, current and resistance. Ohm's Law can be written as a word equation: voltage = current × resistance Or using symbols to represent the quantities of voltage (V), current (I) and resistance (R): V = I × R In fact it can be written three ways and you can pick the version that's best for your purpose: V = I × R I = V R R = V I The VIR triangle - a way to remember Ohm's Law V I R You can use the VIR triangle to help you remember the three versions of Ohm's Law.

• To calculate voltage, V: put your finger over V, this leaves I R, so the equation is V = I × R • To calculate current, I: put your finger over I, this leaves V over R, so the equation is I = V/ R • To calculate resistance, R: put your finger over R, this leaves V over I, so the equation is R = V/ I Use the right units For most electronic circuits the amp is too large and the ohm is too small, so we often measure current in milliamps (mA) and resistance in kilohms (k ).

1 mA = 0.001 A 1 k = 1000. The Ohm's Law equations work if you use V, A andor if you use V, mA and k. It is vital to use the right units for the three quantities in Ohm's Law, otherwise calculations will give the wrong values. You can use either of these two sets of units: V = voltage in volts (V) I = current in amps (A) R = resistance in ohms ( ) or V = voltage in volts (V) I = current in milliamps (mA) R = resistance in kilohms (k ) You must not mix these sets of units in the equations so you may need to convert between mA and A or k and.

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This portable amp is an open hardware project designed by ElectroSmash using only free / open-source tools. The preamp stage with two J201 transistors is designed to give a tube-like sound, the BMP tone stage is able to produce a big range of tones and the LM386 output stage can drive any kind of speaker, from headphones to a Marshall 2x12 resistor 15k.

This project is perfect as a room practice amplifier loaded with all the features of the big amps: • Tone/Volume/Gain controls. • Speaker/Cabinet output. • Headphones output with integrated attenuator switch.

• Aux/mp3 input. • Battery Clip. • 9V DC boss style power input jack. 1Wamp Schematic The circuit can be broken down into 5 simpler blocks: JFET Input Stage, Tone Control, JFET Booster, LM386 Power Amplifier and Power Supply: The functionality is simple: The input stage isolates the amp from the guitar, keeping the signal quality and avoiding tone sucking.

Then the tone control shapes the frequency response adding more bass/treble to the mix. The JFET booster will recover the signal after the tone control and prepare it to the Power Amplifier stage that delivers up to 1W.

The aux/mp3 input adds any line level input signal to the guitar sound, allowing to practice with metronome/mp3/youtube backing tracks. What is a pre-amplifier?: A pre-amplifier is the part that precedes power amplifier (JFET Input Stage, Tone Control, and JFET Booster). It prepares the signal for further amplification or in other words, the pre-amplifier is just a circuit that does some preparing for the signal, usually coloring and integrating small gain stages with good impedance matching, tone controls, and filter elements.

This part does not generate any power to drive a speaker. What is a power amplifier?: The LM386 power amplifier block will amplify and deliver the voltage and more important the current to drive the load (headphones/speaker). The stage will define the wattage of the amp, and should just deliver power without adding any color to the signal. Order 1Wamp online. There are 2 options in the online shop : • Order the Full Kit:This kit includes the PCB, Cover and all the components to build 1Wamp at home.

• Order only the PCB. It uses easy-to-find standard components and you can build the kit yourself. If you have any question, contact us: • There is a cool guide explaining How to build 1Wamp in 5 Steps • All the Kicad native files, Schematic and Bill of Materials are free. • In 1Wamp Forum you can check how to fit the PCB in an enclosure, use the light-plates, etc.

Power Supply Stage: The power stage provides 9 volts to all the circuit stages, giving also protection against reverse polarity connections and additionally it filters the power line to remove any noise. • The 2.1 jack connector CONN4 can take any boss type 9V adapter (negative polarity), it is a nice idea to use one because power amplifiers drain batteries pretty fast by definition.

This connector will automatically disconnect resistor 15k battery from the circuit when an external 9V wall adapter is plugged. • The stereo guitar input jack is used as an on-off switch, connecting the battery (-) terminal to ground when the guitar jack is connected. When the mono input guitar jack is inserted, the points GND_B and GND_A are linked powering up the circuit. • Diode D 1 is a resistor 15k protection diode, securing the amplifier against accidentally reversed power connections.

In this case, the 1N5817 diode is used because it resists up to 20V in a reversed connection and it has a low Resistor 15k F=0.4V, so the final power supply will be 9 - 0.4= 8.6V giving more headroom for clean sounds. A ny other general use diode like the 1N4148/1N4001 could be used as a substitute. • The LED D 2 will light when the circuit is ON (9V Battery or adapter + guitar connected). A high-efficiency diode is used to minimize the current used in this task.

• C 9, R 15, C 10, and C 11 are a low pass filter aimed to remove all the ripple and noise from the power line. The placement of the components in the circuit is critical: • C 9 is close to the LM386 to decouple it. • R 15 and C 10 C 11 form the most important resistor 15k of the filter and it is located between the power-amp and the pre-amp.

• C 11 is located close to the input stage to decouple it. The cut-frequency of the filter is defined by R 15 and C 10 and C 11 and can be calculated following the equation: $f_{c}=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot R_{15}\cdot (C_{10}+C_{11})}=\frac{1}{2\pi \cdot 1K \cdot (220uF+100nF)}=0.7Hz$ So, any humming noise over 0.7Hz will be removed by this filter.

There is more info about this filter and how to remove hum from LM386 designs in the Layout Section. JFET Input Stage The input stage is JFET pre-amplifier based on a Common Source Class-A amp with a high input impedance and medium output impedance. The JFET preamps became very popular in guitar circuits because they are simple, easy to build and able to deliver warmth tones. There are several famous guitar pedals that use this circuit topology: - The Tillman Amplifier, it uses an R2=6.8K and R3=2.2K, famous for giving a tube-like sound with 6dB of gain and asymmetrical clipping. - The Fetzer Valve is popular as a stand-alone booster and as a building block in larger circuits. It is based on a white paper by Dimitri Danyuk "Triode Emulator".

It proposes the use of a carefully chosen source resistor on the JFET amplifier to mimic a vacuum tube sound. It uses R2= 10K and R3=1K, giving a high gain of 14 dB.

- Low gain JFET preamp: The Tillman and Fetzer valve introduce a big amount of gain and sometimes could make difficult to get resistor 15k tones.

If you prefer natural clean sounds and light overdrive R2= 2.2K and R3=1K can also be used, giving soft resistor 15k and mellow saturation. The whole 1Wamp circuit includes 2 of this JFET booster stages, so you can also combine these topologies as you like; Low Gain + Low Gain, Fezter + Low Gain, Tillman + Fetzer, etc.

• D 3 and D 4 are 5.1V 1-Watt zener diodes. They are surge protection against static discharges, they clamp the input signal if the levels exceed ±5.1V. They are optional but JFETs have a sensitive gate and they can blow just resistor 15k a spark at the jack in a dry day.

The 1N4733A part is used here due to its easy availability but any 5.1V 1W zener like the BZX85 5.1V could substitute it. • R 1 determines the input impedance and references the JFET gate to ground. The value of this component is not critic, anything from 100KΩ to 2MΩ will work, you can read more about this resistor in the 1Wamp Input Impedance section. • R 2 is the source resistor, it defines the I D bias current through the JFET and R 3 is the drain load resistor.

You can read how to calculate them in the next section. How to Calculate R S and R D in a JFET Common Source Amplifier: Intro - Background The source resistor R S (R 3 or R 7 in 1Wamp) and the drain resistor R D (R 2 or R 8 in 1Wamp) define all the important parameters and sound of the pre-amp. There are plenty of ways to design and calculate the components for a JFET amp: graphical methods, mathematical, experimenting. sometimes misleading and confusing. Here we describe the simplest way resistor 15k my opinion) to design and calculate Resistor 15k G, R S, and R D for this particular amp called "Self Biased Common Source JFET Amplifier".

• R G: The Gate resistor, keeps the gate voltage at 0V, it also defines the input impedance and prevents signal loading. • R S: The Source resistor, defines the bias point of the amplifier. • R D: The Drain resistor, defines the gain of the amp. Fixed values: A JFET transistor has 2 important fixed parameters: • I DSS: Saturation Drain Current.

It is the maximum current that flows through a JFET, which is when the gate voltage V G is 0V. • V P or V GS(off): The pinch-off voltage, it is the voltage required to shut down a JFET. These parameters are resistor 15k in the datasheet with big tolerances. In the J201, for example, V GS(off) goes from -0.3 to -1.5V and I DSS could be anything from 0.2 to 1mA. Note that these values change from one transistor to another: There is a JFET tester designed by RunoffGroove that can accurately measure the I DSS and V GS(off) in a JFET.

From our experience, measuring one hundred reliable J201 JFETS resistor 15k can average this values to: • I DSS= 0.7 mA (average value). • V GS(off)= -0.8 V (average value). How to calculate R S and R D in 5 steps: The Midpoint Bias method sets the transistor to the midpoint of its transfer curve, allowing maximum headroom (the drain current swings with a maximum span between I DSS and 0 without clipping): • Calculate I DSS and V GS(off) from the datasheet, taking average values or using a JFET matcher.

• Calculate I D: as I D = I DSS/2 setting the midpoint bias. • Calculate V Resistor 15k using the formula V GS= V GS(off)/3.4 $gm = \frac{2I_{DSS}}{-V_{P}-} \cdot (1-\frac{V_{GS}}{V_{P}})$ These 5 steps can be summarized in the following image: In this ideal mid-point biasing, the gain of the amp is limited by the values of R D and R S which in turn are limited by the intrinsic characteristics of the JFET (I DSS and V GS(off)), to trim the gain the value of R D can be reduced/increased.

The midpoint is often traded for higher gain; changing the value of R D will modify the gain, but the clipping will be more prone to happen. To finish this notes about the JFET biasing, it should be said that there is some mysticism biasing the JFET, the values of R D and R S can be tuned by ear for the best sound or following complex mathematical analysis trying to replicate the tube sound.

Some designers prefer not to follow the ideal mid-point biasing and make their designs with some variations, to see that we will study the Tillman, the Fetzer Valve and the Low Gain Fet: J201 Tillman pre-amp: • R G = 1M Ω • R S = 2.2K Ω • R D = 6.8K Ω • Considering I DSS = 0.7mA and V GS(off) = V P = -0.8V and V CC=9V.

There is no simple formula to calculate I D and Resistor 15k GS. you will need to solve a system with 2 ecuations resistor 15k 2 variables (I D and V GS): I D= I DSS(1-V GS/V GS(off))^2 V GS=-I D*R S Resolving we get the values: $\\ I_{D}^{2}\cdot(7.5)-I_{D}\cdot (6.9)+1=0)$ Resolving thie quadratic equacion (you can use any online calculator, or make the maths) We get 2 possible solutions, ID= 0.73mA or 0.18mA.

ID

These will make the amp to have a low amout of gain and the clipping will happen easier in the positive semicycle of the signal. The designer was not looking for a high-gain design and due to the popular acceptance of this circuit seems that it also sounds good.

J201 Fetzer Valve • R G = 1M Ω • R S = 1K Ω • R D = 10K Ω • Considering I DSS = 0.7mA, V GS(off) = V P = -0.8V and V CC=9V. Summarizing the fetzer valve, Runoffgroove uses 2 equiations derived from Danyuk Triode Emulator paper to calculate R S and R D: Rs = 0.83 * -Vp- / Idss = 0.83 * 0.8 / 0.7 = 0.9K Ω approx.

to 1K Ω Rd = 0.9 * (Vcc - 2*-Vp-) / Idss = 0.9 *(9 - 2*0.8) / 0.7 = 9.5K Ω approx to 10K Ω Using a similar approach that in the Tillman amp we can calculate the bias points: • I D= 0.27mA • V GS=-0.27V • V D=6.3V • A V=14dB. In the Fetzer amp, the value of I D is very close the IDss/2, allowing a nice big span of this current. The value of R D also makes V D close to its ideal value.

In this point, the transistor has a big amount of gain and seems that replicates the behavior of a vacuum tube. J201 Low Gain Fet: • Resistor 15k G = 1M Ω • R S = 1K Ω • R D = 2.2K Ω • Considering I DSS = 0.7mA and V GS(off) = V P = -0.8V Following once again the maths of the Tillman amp ID and VGS can be calculated: • I D=0.27 • V GS=0.27 • V D=8.4V • A V=1=0dB.

The current in the Low Gain JFET amp is designed to be ideal (I DSS/2), and the V D point is intentionally shifted from the midpoint biasing, it will make the signal to clip in the positive semi-cycle easily. The LM386 does not need a high-level input so placing this amp/buffer before it, improves the sound quality. Amplifier Input Impedance: These JFETs have the advantage over bipolar transistors of having an extremely high input impedance along with a low noise output making them ideal for use in amplifier circuits resistor 15k have very small input signals.

The JFET input impedance can be considered infinite and only the value of the gate resistor (R 1) will define the total value of it Z IN= ∞ // R 1 = R 1 = resistor 15k The rule of thumb is to interface the guitar to an input impedance that is at least 1MΩ, it will keep the signal uncorrupted as foundations for the next stages avoiding tone sucking.

Tone Control The passive tone control is Big Muff Pi style, following a classic simple and effective design that generates a great variety of tones. This topology is a combination of a high pass filter (C 1R 5) and a low pass filter (R 4C 2) that are mixed together by a linear potentiometer POT1.

The cut-off frequencies of both filters are designed so that their interweaving effect introduces a middle-frequency scoop/notch at 800Hz (see the graph below) when the potentiometer is set to middle. • High-Pass filter cut frequency $f_{c}=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot R_{4}\cdot (C_{2})}=\frac{1}{2\pi \cdot 47K \cdot 10nF}=338Hz$ 1Wamp Tone Control Frequency Response: Find below the frequency response, showing from blue to red all values of resistor 15k tone potentiometer: The green response line has the tone pot set at mid point showing the 800Hz scoop.

There is an overall 7dB loss and at the notch the loss is about -10dB in total at 800Hz. The blue and red colour curves have the tone at full bass/treble respectively. T here are some tips using BMP based tone controls: • To play clean sounds, the best is to use the pot more to the side of the treble, it will attenuate overloading bass signals and the resulting sound resistor 15k be more sparkly and clean.

• To play rock/hard/metal any position is good, the distortion will be more metal-heavy on the bass side and more punk-fast on the treble. JFET Booster Stage. This second JFET stage is identical to the first one, resistor 15k is designed primarily to recover the volume loss of -7dB during the passive tone stack and to introduce more harmonic content to boost the tube sound. R 6, R 7, and R 8 are the gate, source and drain resistors. Their functionality is exactly the same as the R 1, R 2 and R 3 resistors in the Input Stage.

If you want to learn more about these resistors and how to calculate them check the Input Stage section. LM386 Aux/mp3 input This auxiliary input mixes the guitar signal with an additional line-level input from a laptop/mp3/music player just before the power amplifier. Doing this it is easy to practice with backing tracks, metronomes or drum bases. • R 9 and R 10 resistors in series with the aux input prevent signal mixing problems while adjusting for differences in input strength between the line resistor 15k and pre-amplified guitar signal.

Any value between 10KΩ and 33KΩ will work without problems. • C 12 is a 100nF capacitor, placed to reduce any hum or interference that the input mini jack can catch if resistor 15k is connected to it. An Aux/MP3 player is a low-impedance source.

Placing a buffer in this input would be perfect (adding circuit complexity), but you may be able to work without them. The LM386 has a 50K input impedance, so using summing resistor of any more than 50k is not ideal as the input voltage would be cut in half when using a 50k resistor (neglecting the booster stage impedance).

The volume of the aux input is adjusted from the external device, for circuit simplicity, there are not pot to reduce the input level. Note also that the mp3/aux input is resistor 15k fed into the LM386 and using high distortion levels the aux input might suffer some distortion.

This is the little price to pay for having a simple and practical direct input. Additionally, this input can also be used to connect a second guitar or a bass guitar with a jack to mini-jack adapter. LM386 Power Amplifier Stage.

The main power amplifier stage is based on the LM386 audio integrated amplifier. It is a popular choice for low powered guitar amplifiers due to its low quiescent current and ability to run on 9V. It has been used in a lot of popular amps like the Smokey Amp, the Little Gem, the Ruby Amp, the Marshall MS-2 and the Noisy Cricket.

• C 4 is a 47nF input capacitor, it prevents any DC voltage being presented to the amplifier's input. It also affects the circuit's bass response, changing this value to a higher capacitance (100nF) will make it more bassy but also more muddy, values from resistor 15k to 47nF sound great.

• The POT2 functionality is explained in the Volume Potentiometer section. • R 11 resistor is placed for the mp3/aux input which is connected to the same point as the TP4 (Test Point 4). If the POT2 is maxed down, the input of the LM386 will be grounded and the aux/mp3 signal won't be amplified. Connecting this series resistor a minimum load is always guaranteed for the auxiliary input. • The POT3 and R 16 functionality are described in the Gain Potentiometer section.

• The C 5 capacitor from pin 7 to ground avoids the power supply noise to be amplified and reach the output. In this way, the high-gain input stage of the chip is isolated from the supply noise hum, transients, etc.

• R 12 and C 6 form the Zobel Network, its function is to make the power stage more stable removing oscillation, the values used, 10Ω and 47nF are standard because this network is aimed to compensate the load (speaker or headphones), not the amplifier, and the load is normally generic in audio amplifiers.

The resistor is chosen to equal the nominal resistance (32Ω, 8Ω, 4Ω, etc.) • The capacitor is calculated using C= Le/R2, where Le= inductance of speaker's coil. • The physical location of this components is critical, they should be placed as close as possible to the chip, in some occasions Zobels mounted careless around the PCB cause oscillation. With the LM386, the best values are a 10 and a 47nF, they give the smoother distortion, raising the values of the R or the C will make the distortion more crispy and rough.

• R 13 will reduce the volume for the headphones, any value between 300Ω and 1KΩ will work, the higher the value the lower the volume at the headphones. This output attenuator formed by the SW1, C 7, C 8, and R 13 is resistor 15k in the LM386 Output Attenuator section. Volume Potentiometer. The POT2 Volume potentiometer limits the amount of signal into the LM386. As the Resistor 15k is increased, you will start getting nice breakup.

Gain Potentiometer. Why POT3 and R16 are mounted in parallel? The range of values of PCB mounted potentiometers on the market is limited, finding resistor 15k pots with the correct footprint and shaft length could be difficult. Placing 50K potentiometer (easy to find) and 1K Ω simple resistor in parallel will create a 1K Ω potentiometer: • With the POT3 at max (50K): 50KΩ//1KΩ= (50Kx1K)(50K+1K)= 0.98KΩ = 1KΩ approx • With the POT3 at min (0K): 50KΩ//1KΩ= ( 0Kx1K)( 0K+1K)= 0 The resulting potentiometer will be logarithmic instead of linear, but with a high gain amp like this, it is not bad to have a more sensitive pot in the first half of the potentiometer.

However, if you are able to find a 1K potentiometer you can place it instead of the parallel combination. LM386 Voltage Gain Calculation The potentiometer (1K as explained above) placed between pins 1 and 8 to adjust the gain from 41 (28dB) to 200 (46db) resistor 15k the general LM386 voltage gain formula taken from the datasheet: Where Z 1-5 and Z 1-8 are the impedances between the respective pins. Note that Z 1-5 internal resistance is 15K Ω and Z 1-8 is 1.35K Ω.

If you want to read more about how to calculate the voltage gain, you can read the Voltage Gain Calculation in the Ruby Amp. LM386 Resistor 15k Attenuator. The output power of the LM386 is too high for a pair of headphones. An average pair of headphones only need 1mW (into 32Ω) for a reasonable good volume. Depending on the LM386 model, it is able to deliver up to 1000mW (1W), so in order to reduce this output power below the threshold of pain, a series resistor is placed.

This auxiliary load will take part of the power giving to the headphones the right amount of it. Frequency response resistor 15k the output attenuator: Placing an output attenuator will modify the frequency response, reducing the amount of bass into the headphones.

• Without attenuator (purple plot above): There is a low pass filter formed by C 7 (220uF) and the speaker load (let's consider it resistor 15k 8Ω driver), the cut-frequency is 90Hz (calculated as fc=1/(2 πRC)), harmonics below 90HZ will be attenuated. Guitar signals do not have much content at that frequencies and also rolling off the bass helps small speakers from farting out. In fact, if you have a small speaker and it farts you should reduce this cap to something like 47-100uF (rolling the bass around 400Hz).

• With attenuator (blue and red plots above): The extra resistor in series and the load (32Ω headphones ) will roll off the bass below the audible frequencies. For this series resistor, any value between 300Ω and 1KΩ will reduce the volume to an acceptable level resistor 15k most headphones.

Some people use just a 10Ω resistor but from my experience, the volume is still too high. LM386 Clipping - Overdrive - Distortion: Two types of clipping/distortion and a combination of them can be resistor 15k with an LM386 power amplifier: • Clipping at the output of the LM386 by reaching the limits of the output voltage swing: In this circuit, the LM386 has always minimum gain of 41 (32dB), the output will clip if the signal reaches 8Vpeak-to-peak using a 9V power supply.

The maximum input voltage that will make the output clip is 8Vpp/41=195mVpp, any voltage over this level will clip the output creating distortion tones. The Volume potentiometer (POT3) is placed to attenuate the incoming signal below this 195mVpp (clean tones) or over it (crunch-distortion). • Clipping at the input of the LM386 by the overload of the IC input limits: The LM386 has an input voltage limits of ±0.4V (listed in the datasheet).

If the input signal goes even higher over ±0.4V the input stages of the LM386 will saturate creating even more distorted sounds. 1Wamp Layout. The design and layout of the power supply in audio circuits with a pre-amp and power-amplifier stages is critical. If the power from the battery/adapter jack is given to the circuit following a wrong path, the noise of the power-amp could be added to the pre-amp stage, resulting in a positive feedback and creating noise or oscillation commonly called motor-boating.

To avoid this, the power should be connected following this block diagram: Rules to minimize noise in audio circuits: • Place a CRC network (low-pass filter) between the power-amp and the pre-amp. This is something that has been there for decades, if you check any old Marshall/Fender valve amplifier schematic you will spot a CRC between the power valves and the pre-amplifier (usually a 10K resistor and a cap of tens to hundreds of farads) • Place filter capacitors close to the part to be decoupled.

• Keep power and GND traces away from noise sources or critical components. • Route the power and GND traces as thick as possible. Star grounding: Ground is the common reference potential, commonly determined to be zero volts. This ground is the shared return path from the power supply to all the stages of the circuit. • Connecting the blocks of the circuit to ground in series will work, but a small voltage drop will be created in the ground signal due to the high currents and the (small) resistance of the ground track.

The input stage is very sensitive to common noise introduced through the ground line, this noise could be added to the input signal and in the worst case create oscillation/positive feedback. • Connecting the blocks of the circuit in parallel finishing in a single point (star) the ground variances and interferences between parts is minimized.

In the above image the center of the star ground is indicated, from this all the green ground tracks for the different subsystems (input jack, led, input stage, tone control, booster, power amp, output jack). These tracks flow in parallel and with similar lengths minimizing common noise.

1Wamp Bias Points and Signals: The most important DC bias points resistor 15k the 1Wamp are shown. It can be useful for troubleshooting: note: Y our values should be all shifted a bit up resistor 15k down, depending on your power supply levels. For this graph, Vcc is ideal and equal to 9V. - To get this voltage values, the POT1 (Tone) is in mid position, POT2 (Vol) is at maximum value and POT3 (Gain) is resistor 15k the minimum value.

- V D1 voltage is slightly lower than the calculated in the Tillman pre-amp section (7.8 VS 7.4). This is due to the loading of the tone control. 1Wamp Signals: Using an oscilloscope the most important points of the amplifier are measured: input signal (TP1), after the first JFET stage (TP2), after the tone control (TP3), after the second JFET stage - input of LM386 (TP4) and output signal.

These waveforms were taken using different JFET topologies: with 2 Tillman JFETS, with 2 Fetzer Valves, and with 2 Low Gain JFETs: • The signals above shows the amplification and waveforms at all the test points (TP) of the circuit using a Tillman topology in both transistor amplifiers.

• The input stage has a gain of 4dB approx, slightly reduced from the calculated in the Input Stage section due to the loading of the Tone Stage and the real parameters of the JFET. • The Tone Control reduces the amplitude of the signal -10dB at 1KHz as expected and the last amplifier stage gives again 4dB of Gain. • The last two graphs show the output of the amplifier when the gain is set to its minimum and maximum value. This output signal goes from clean to clipping giving a nice range of action and sounds. • Resistor 15k images above show the signal of the circuit using the Fetzer Valve topology in both transistor amplifiers. In general, this circuits gives more gain than the Tillman, resulting in a higher and more clipped output signal.

• The input stage has a gain of 11dB approx, slightly reduced from the calculated in the Input Stage section due to the loading of the Tone Stage and the real parameters of the JFET. • The Tone Control reduces the amplitude of the signal -10dB at 1KHz as expected and the last amplifier stage gives again 11dB of Gain. • The last two graphs show the resistor 15k of the amplifier when the gain is set to its minimum and maximum value. This output resistor 15k goes from clipped to supper-clipped being perfect resistor 15k overdriven tones and hard rock sounds.

• The images above show the signal of the circuit using the JFET Low Gain topology in both transistor amplifiers. In general, these circuits give less gain than the Tillman, resulting in a range of clean and light asymmetric overdriven tones. • The input stage has a gain of 0dB, the Tone Control reduces the amplitude of the signal -10dB at 1KHz as expected and the last amplifier stage gives again 0dB of Gain.

It might seem that the guitar signal at the input of the LM386 is too low (63mVpp) but it's not a problem, the LM386 does not require high-level waveforms at its input, in fact, signals over 195mVpp will be clipped as seen in the Clipping Section. The last two graphs show the output of the amplifier when the gain is set to its minimum and maximum value. The output signal goes from clean to light asymmetric overdrive. note: - For all the images, the input signal is a 1KHz sinusoid with 200V PP, comparable with an average guitar signal.

- The POT1 (Tone) is set to mid, the POT2 (VOL) gain to max and the POT3 (Gain) varies from min to max in the last 2 images. 1WAmp Bill of Materials / Part List: The components for the 1Wamp are easy-to-find through-hole parts with the minimum number of references.

There is resistor 15k of alternatives and replacement parts although the J201 JFET is a bit tricky. Find below the complete bill of materials, with mouser/ resistor 15k references and alternatives: 1Wamp Bill of Materials Reference Qty Value Description Mouser Farnell Capacitors C1 1 6.8n CAP, FILM, PET, 6.8NF, 100V, RAD R82EC1680Z350J C2 1 10n CAP, FILM, PET, 0.01UF, 100V, RAD R82EC2100DQ50J C3,C4,C6 3 47n CAP, FILM, PET, 0.047UF, 100V, RAD R82EC2470DQ60J C5,C11,C12 3 100n CAP, FILM, PET, 0.1UF, 100V, RAD R82EC3100DQ70J C7,C8,C9,C10 4 220uF Aluminum Electrolytic Capacitor 16V REA221M1CBK-0811P Resistors R12 1 10R TH Metal Film, 10R, 1/4W, ±1% MF25 10R R13,R15,R16 3 1K TH Metal Film, 1K, 1/4W, ±1% MF25 1K R3,R8 2 2K2 TH Metal Film, 2.2K, 1/4W, ±1% MF25 2K2 R2,R7,R11 3 6K8 TH Metal Film, 6.8K, 1/4W, ±1% MF25 6K8 R5,R9,R10,R14 4 22K TH Metal Film, 22K, 1/4W, ±1% MF25 22K R4 1 47K TH Metal Film, 47k, 1/4W, ±1% MF25 47K R1,R6 2 1M TH Metal Film, 1M, 1/4W, ±1% MF25 1M Pot1,Pot2,Pot3 3 50K Potentiometers 9MM 50K V/ADJ RK09D113000D Connectors CON1, CON3 2 6.35 jack Neutrix 1/4 ST Chrome Conn PCB NMJ6HCD2 CON2 1 3.5 jack Jack 3.5 mm st - CLIFF 4 POLE, PCB FC68125 CONN4 1 2.1 jack DC Power Conn 2.0mm PCB Jack KLDX-0202-AP-LT MJ-179PH Others D1 1 1N5817 Schottky Diodes Vr/20V Io/1A 1N5817 D2 1 LED Standard LED - TH 3MM LED WHITE VLHW4100 D3,D4 2 1N4733A Zene Diode 5.1V 1W ZENER 1N4733A 8pin dip socket 1 8Pin socket IC Sockets 8P DUAL 4808-3000-CP Q1,Q2 2 J201 Plastic Knobs 3 6.35mm knob Knob 6.35 mm shaft size.

450-2023-GRX SW1 1 toggle switch Toggle 3-Pin SPDT ON-ON 612-100-A1111 9V Battery Conn. 1 Battery Clip 9V Battery Contacts 26AWG 121-0526/I-GR U1 1 LM386 Audio Amplifier LM386N-4/NOPB Mechanical PCB 1 1Wamp PCB Plexiglas Cover 2 - Nylon Spacer 4 m3x16 Spacers M3 x 16mm nylon R30-1611600 M3x12 screws 8 - M310-PRSTMCZ100 Batt. optional clips 2 - 4.8X0.5MM TAB38250568 * Additional Comp.

R2, R7 2 10K TH Metal Film 10K, 250 mW, ± 1% MF25 10K R3, R8 2 1K TH Metal Film, 1K 250 mW, ± 1% MF25 1K *Additional components:The additional 2x10K and 2x1K will allow you to configure the JFET Stages as you like so you can choose between the J201 Tillman pre-amp (default), the J201 Fetzer Valve or the J201 Low Gain Fet. The difference between them is the amount of gain that they introduce (5.9dB, 14dB, and 0dB respectively).

You can find more info in resistor 15k JFET Input Stage section. Capacitors: Electrolitics, Film, Ceramics .? For big values (>1uF) use aluminum electrolytic, for medium size (1nF - 1uF) use Film and for small values (<1nF) use ceramics. If you are not sure about using ceramics or film somewhere go for film; film capacitors are generally preferred over ceramics in audio path applications. There is a great article about capacitors for audio by BeavisAudio.

References: Fetzer Valve Amplifier by RunoffGroove. Tillman Amplifier by Donald Tillman. Teemuk Kyttala Solid State Guitar Amplifiers, the Holy Scripture. JFET Basics by Kenneth A. Kuhn Common Source JFET Amplifier by Electronic Tutorials. JFET Preamplifier Circuits by Mike Martell. Smokey Amplifier by ElectroSmash. Ruby Amplifierby ElectroSmash. Spice model for the J201 JFET Transistor: * J201 with VGSoff=-0.8V and IDSS=0.6mA .MODEL J201 NJF (VTO=-0.8 BETA=0.9375M LAMBDA=2M IS=114.5F RD=1 RS=1 + CGD=4.667P CGS=2.992P M=.2271 PB=.5 FC=.5 VTOTC=-2.5M BETATCE=.5 + KF=604.2E-18) If you want a JFET with a certain value of VGSoff and IDSS, just change the model so: VTO = VGSoff BETA = IDSS / (VGSoff^2) All credits to stm in diystompboxes.com Spice model for the 2N5457 JFET Transistor: * 2N5457 with VGSoff=-1.6V and IDSS=3.3mA .MODEL 2N5457 NJF (VTO=-1.6 BETA=1.29M LAMBDA=2M RD=1 RS=1 CGD=6E-12 + CGS=2.25E-12 KF=6.5E-17 AF=0.5) Spice model for the MPF102 JFET Transistor: * MPF102 with VGSoff=-2.5V and IDSS=6mA .MODEL MPF102 NJF (VTO=-2.5 BETA=0.96M LAMBDA=5M RD=1 RS=1 CGD=1.54248P + CGS=2.567P PB=1.49 KF=7.90591F AF=499.953M) Thanks for reading, all feedback is appreciated Some Rights Reserved, you are free to copy, share, remix and use all material.

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Resistor Color Code Calculator is an interactive online Calculator to calculate the resistance value based on color bands or color-coded stripes on a resistor. There are many different types of resistors in electronics today. A resistance calculator for the color code of resistor is an efficient way to help you to find the right one for your needs, whether it is for a circuit or just to know what type of resistor you have in your box.

Known as ohmmeter calculator, the Color Code resistor calculator is the integration of 4 Band, 5 Band and 6 Band Resistor Color Code Calculators. So you can use this parallel resistor calculator to make basic and complex electrical circuits for both home and industrial purposes. And the following will show you how to use this tool to read the color code of resistors, calculate the resistor value in Ohms (Ω) for 4-band, 5-band and 6-band resistors based on the color code on the resistor and identify the resistor's value, tolerance, and power rating.

The Standard Resistor Color Code Chart How to Use the Resistor Color Code Calculator The online resistor calculatoris a tool by Utmel Electronic used to calculate resistor values for 4 band, 5 band, and 6 band resistors, in the range of ohms, Kilo Ohms, and Mega Ohms typically.

And this resistance calculator is developed to calculate the color code using the resistor color codes on their surface.Just select the right color corresponding to each column and you can get the Resistor value on the right of the calculator immediately. Examples: Calculating 10k/100 Ohm Resistor Color Code Take a 4-band resistor as the example, 10k ohm resistor color code 4 band is: Brown-Black-Orange-Red.

So the 1st band of Color: Brown, 2nd band: Black, Multiplier: Orange and Tolerance: Red. Thus, the output of resistor value is 10K ohms 2%. And the below picture shows you the 100 Ohm Resistor Color Code for 4-band resistors.

100 Ohm Resistor Color Code for 4-band Introduction of Resistor Resistors are resistor 15k used in electrical components with the aim of restricting the flow of electric current. They are usually tiny components with wire leads protruding from all sides. Resistors are special electronic components in resistor 15k. It is made with the purpose of resistor 15k precise quantity of electrical resistance.

The range of resistors may be from less than 1 Ohm (Ω) to over 20 mega Ohms (Ω) or 20 million Ohms (Ω). And there are two types of resistors: variable resistors and fixed resistors. A variable resistor can provide different values of resistance, however, the fixed resistor just has a single value.

Meanwhile, there are 4 main classes of fixed resistors: carbon-composition resistors, Resistor 15k resistors, wire wound resistors, and surface-mount resistors. Resistor Color Bands How to Read a Resistor Color Code Chart for 3/4/5/6 Band Resistors Generally, the carbon-composition resistors have 3 to 6 resistor color bands. And the below electrical color code resistor chart shows you the resistor strips of the 3 band type, 4 band type, 5 and 6 band type.

Compared with a 4-band resistor, a 5-band type is more precise because of its third significant digit. And a 6-band resistor has the 6th band, which is a temperature coefficient band. From the following Resistor color code chart Calculator, we know that each color resistor 15k resistor represents a number if it's found on 6-band and 5-band type from 1st to 3rd band or a 4-band resistor from the 1st to 2nd.

And it is a multiplier if it is located on the 4th band of 5-band and 6-band type or the 3rd band of a 4-band resistor. You can get the tolerance values of a resistor on the 4th band for the 4-band type according to the 4 band resistor color code chart and the 5th for the 5-band and 6-band type through the below resistor color chart 5 band and 6 band. A 6-band type resistor resistor 15k the 6th band, which shows you the temperature coefficient.

And this value indicates how much the actual resistance value of this 6-band resistor changes when the temperature changes. How To Read Resistor Color Code? The easiest way to identify a resistor Color code is to know which colors represent the most significant digits.

The following steps will guide you in reading a resistor color code. 1) Look for the colored bands on the resistor's body. 2) Determine which of these colors have a leading role in representing numbers. 3) Identify the numbers represented by these colors and their position. 4) Read off each of these digits from left to right on the band where it's located. What is the purpose of resistor color codes? Instead of written text, a color code is used to indicate the value, rating, or tolerance for very small electronic components.

Resistors are available in four, five, or more color bands, with a four-band color code being the most common. The first and second bands represent the first and second significant digits of the ohm value, respectively, while the third band represents the decimal multiplier.

After that, there's a slight gap to help you distinguish between the component's left and right sides, followed by the fourth band, which indicates the resistor's tolerance. Resistor Color Code Explained 4 band Resistor Color Code IEC 60062 defines the color coding for resistors as an international standard. Different colors reflect significant figures, multiplier, resistance, reliability, and temperature coefficient in the resistor color code shown in the table below.

The location of the color band on the resistor determines which of these the color refers to. There is a spacing between the third and fourth bands in a standard four-band resistor to show how the resistor should be read (from left to right, with resistor 15k lone band after the spacing being the right-most band).

4 Band Resistors Color Code Table Color 1 st Band (1 st Figure) 2 nd Band (2 nd Figure) 3 rd Band (Multiplier) 4 th Band (Tolerance) Temperature Coefficient Black 0 1 250 ppm/K(U) Brown 1 1 10 ±1% (F) 100 ppm/K(U) Red 2 2 100 ±2% (G) 50 ppm/K(U) Orange 3 3 1000 ±0.05% (W) 15 ppm/K(U) Yellow 4 4 10000 ±0.02% (P) 25 ppm/K(U) Green 5 5 100000 ±0.5% (D) 20 ppm/K(U) Blue 6 6 1000000 ±0.25% (C) 10 ppm/K(U) Violet 7 7 10000000 ±0.1% (B) 5 ppm/K(U) Grey resistor 15k 8 100000000 ±0.05% (L) 1 ppm/K(U) White 9 9 1000000000 Gold 0.1 ±5% (J) Silver 0.01 ±10% (K) None ±20% (M) 4-band resistor color code chart Significant figure component: four-band resistor The first and second bands in a standard four-band resistor reflect significant figures.

Refer to the figure above with the green, red, blue, and gold bands for this illustration. The green band represents the number 5 in the table below, while the red band represents the number 2. Resistor 15k The third, blue band, is the multiplier.

Using the table, the multiplier is thus 1,000,000. This multiplier is multiplied by the significant figures determined from the previous bands, in this case, 52, resulting in a value of 52,000,000 Ω, or 52 MΩ.

The multiplier is the third, blue band. The multiplier is therefore 1,000,000 when using the table. This multiplier is multiplied by the significant figures calculated from the previous bands, in this case, 52, for a value of 52,000,000 Ω (or 52 MΩ).

Tolerance: The fourth band isn't always visible, but when it is, it stands for tolerance. The resistor value can be varied by this percentage. In this case, the gold band shows a tolerance of 5%, which is indicated by the letter J. As a result, the value 52 MΩ will differ by up to 5% in either direction, resulting in a resistor value of 49.4 MΩ - 54.6 MΩ.

Resistor Color Code 5 Band The 5 band code is used to produce precise and high-quality resistors with tolerances of 1%, 2%, or less. The regulations are the same as in the previous system, with the exception of the number of digit bands. The first three bands will represent the value, the fourth will be the multiplier, and the fifth will be the tolerance. Band (optional) A few resistors include an extra band that indicates either the dependability or the temperature coefficient, which might be confusing for novices.

The failure rate per 1000 hours is specified by the reliability band (assuming that a full wattage being resistor 15k to the resistor). This stripe is most commonly found on 4-band resistors designed for military purposes and is rarely seen in consumer circuits.

Temperature coefficients are becoming more frequent, particularly on high-quality 5-band resistors, as they become an essential element in precision components. For a resistor with a temperature coefficient of 200 ppm, a temperature change of 50°C results in a 1% change in value. The color chart above shows the most frequent values for this band. 5 Band Resistors Color Code Table Color 1 st Band (1 st Figure) 2 nd Band (2 nd Figure) 3 rd Band (3 rd Figure) 4 th Band (Multiplier) 5 th Band (Tolerance) Black 0 0 x 1 Brown 1 1 1 x 10 ±1% Red 2 2 2 x 100 ±2% Orange 3 3 3 x 1k Yellow 4 4 4 x 10k Green 5 5 5 x 100k ±0.5% Blue 6 6 6 x 1M ±0.25% Violet 7 7 7 x 10M ±0.1% Grey 8 8 8 x 100M ±0.05% White 9 9 9 x 1G Gold 0.1 ±5% Silver 0.01 ±10% Five band Resistor Color Code Examples: resistor 15k resistor has colors: Black-Brown-Black-Red-Brown.

The values as, 0/1//0/102 = 10 * 100 = 1K ohm/1K, with a tolerance resistor 15k ±1% for Brown. Therefore, the resistor value is 900Ω to 1.01KΩ More examples of 5-band resistance color code: A resistor colored Blue-Brown-White-Brown-Red The values as, 6/1//9/10 = 619 x 10 = 6190 ohms (6.19K ohms). The tolerance is ±2% for Red. Thus, the resistor value is 6.07KΩ-6.31KΩ 6 Band Resistor Color Code For high precision, Resistors with 6 bands usually have 6 band color codes.

And mostly, the 6th band is colored with brown, which means that the resistance value can change 1000 ppm = 0.1%, for a temperature change of 10 ˚C.

For example, a 6 band resistor colored Orange-Red-Brown-Brown-Green-Red would be 3.21 kΩ with a tolerance of ±1% and a 50 ppm/°C temperature coefficient. Standard EIA Decade Resistor Values The values of resistors are divided into a number of distinct series of recommended or standard resistor values.

The varied values can be spaced in such a way that they relate to the component tolerance or accuracy since the standard resistor values have a logarithmically based sequence. Tolerances for resistors are typically 20%, 10%, 5%, 2%, and 1% respectively. For some resistors, more precise tolerances are possible, although they are not as readily accessible and cost more. Electronic components from a range of manufacturers may be used resistor 15k to these standard resistor values, making sourcing considerably easier and lowering component costs.

EIA PREFERRED OR STANDARD RESISTOR VALUE SERIES E SERIES TOLERANCE (SIG FIGS) NUMBER OF VALUES IN EACH DECADE E3 >20% 3 E6 20% 6 E12 10% 12 E24 5% [normally also available in 2% tolerance] 24 E48 2% 48 E96 1% 96 E192 0.5%, 0.25% and higher tolerances 192 The varied values throughout each decade can be described in a tabular form using the EIA recommended values or standard resistor values.

Despite the fact that current resistor technology allows for resistor 15k tight tolerance levels, there is still a significant benefit to employing resistors from the E3 series.

It streamlines the purchasing and production procedures by reducing the number of various types of resistors used in a design. Typically, designs strive to stick to the E3 or E6 standard resistor values, only employing the E12, E24, E48, or E96 if absolutely necessary.

Digital design, where a pull up or pull down resistor is required, is one example where values can be maintained inside the E3 series. The precise value is unimportant; just a value within the approximate range is required. The value of these resistors can be chosen from the E3 series. Although a little more freedom is required for analogue designs, common resistor values such as E6 or E12 may be employed without issue in most electronic circuit designs.

For high precision and close tolerance requirements, E24, E48, E96, or even E192 series values may be required on occasion: filters, oscillators, measurement applications, and so on.

E3 STANDARD RESISTOR SERIES Because the E3 series resistors are the most regularly utilized, they are the most often used resistor resistor 15k in the electronics sector. They're especially beneficial for resistor settings that aren't crucial in any manner. The number of distinct components in any electronic circuit design may be minimized by sticking to this series, which can assist lower manufacturing costs by decreasing inventory and the additional administration and setup necessary for additional component types in a design.

E6 STANDARD RESISTOR SERIES In the industry, the E6 series resistor values resistor 15k also commonly utilized. They provide you a greater choice of resistor values to choose from. E12 STANDARD RESISTOR SERIES Each subsequent resistor resistor 15k the E12 series is within ten percent of the prior value.

Until recently, 10% tolerance resistors were the standard, but 5 percent (E24) resistors appear resistor 15k be the most used nowadays. Although they may still be found in ancient radios and amplifiers, the cost of a 5% resistor is low enough to make it the standard component in all modern electronic circuits.

Special, more expensive low-tolerance resistor 15k with tolerance values of 2%, 1%, or resistor 15k are utilized in precision applications. E24 STANDARD RESISTOR SERIES The following is a comprehensive list of all E24 series resistors, including shorthand notation, tolerance range, and color coding, ranging from 0.1 ohm to 10 M ohms.

For the E24 series, the fourth band is usually gold (5 percent tolerance). A fifth band may be present, representing the temperature coefficient or dependability. See also the theory behind resistor color coding and the resistor color to value and value to color code calculators for 3, 4, and 5 bands resistors.

E48 STANDARD RESISTOR SERIES The following is a comprehensive list of all E48 series resistors, including shorthand notation, tolerance range, and color code, ranging from 0.10 ohm to 10.0 M ohms. For the E48 series, the fifth band is always red (2 percent tolerance). A sixth band may be present, showing the temperature coefficient or dependability.

See also the logic behind conventional resistor color coding and the resistor color code calculator for 3, 4, and 5 bands.

E96 STANDARD RESISTOR SERIES 1 ohm resistor color code 4 band resistor is brown - black - gold - [Tolerance]. The color code for 1 ohm resistor 5 band is brown - black - black - silver - [Tolerance]. 10 ohm resistor color code 4 band resistor is brown - black - black - [Tolerance]. The color code of the 10 ohm resistor with 5 band is brown - black - black - gold - [Tolerance]. 100 ohm resistor color code of 4 band resistor is brown - black - brown - [Tolerance].

The color code of the 100 ohm resistor with 5 band is brown - black - black - black - resistor 15k. 1k resistor color code of 4 band resistor is brown - black - red - [Tolerance]. 1k ohm resistor Color Code 5 band (namely 1000 ohm resistor color code 5 band) is brown - black - black - brown - [Tolerance].

10k resistor color code of 4 band resistor is brown - black - orange - [Tolerance]. The color code of the 10k ohm resistor with 5 band is brown - black - black - red - [Tolerance]. 100k ohm resistor color code of 4 band resistor is brown - black - yellow - [Tolerance]. The color code of the 100k ohm resistor with 5 band is brown - black - black - orange - [Tolerance]. 1M ohm resistor color code of 4 band resistor is brown - black - green - [Tolerance].

The color code of the 1M ohm resistor with 5 band is brown - black - black - yellow - [Tolerance]. 10M ohm resistor color code of 4 band resistor is brown - black - blue - [Tolerance]. The color code of the 10M ohm resistor with 5 band is brown - black - black - green - [Tolerance]. The color code of the 1.01 ohm resistor for is resistor 15k - black - brown - silver - [Tolerance]. 1.02 ohm resistor color code for 5 band resistor is brown - black - red - silver - [Tolerance].

1.04 ohm 5 band resistor color code is brown - black - yellow - silver - [Tolerance]. The color code of the 1.05 ohm resistor with 5 band is brown - black - green - silver - [Tolerance].

1.06 ohm resistor color code is Brown - Black - Blue - Silver - [Tolerance]. 120 ohm resistor color code is Brown - Red - Brown - Golden - [Tolerance]. 150 ohm resistor color code is Brown - Green - Brown - Golden - [Tolerance]. 2.2k resistor color code 4 band is Red - Red - Red - [Tolerance].

2.2k ohm resistor color code 5 band is Red - Red - Red - Gold/Silver. 20k ohm resistor color code is Red - Black - Orange - Golden 220 resistor color code 4 band resistors is Red - Red - Brown - [Tolerance](Gold for 5% tolerance and Silver for 10% tolerance).

220 ohm resistor color code 5 band is red - red - black - black - [Tolerance]. 20k resistor color code is red - black - orange - [Tolerance]. 22k resistor color code 4 band is red - red - orange - [Tolerance]. 2200 ohm resistor color code 5 band is red - red - black - red - [Tolerance].

330 Ohm Resistor Color Code for 4-band resistor is Orange-Orange-Brown-Golden(tolerance is 5%). 3.3 k resistor color code 4 band is Orange - Orange - Red - Golden.

3.3k resistor color code 5 band is orange - orange - black - brown - [Tolerance]. 33k resistor color code is Orange - Orange - Orange - Golden. resistor 15k ohm resistor color code is Yellow - Violet - Brown - Golden.

15k resistor color code is Brown - Green - Orange - Golden. 47 k resistor color code 4 band is yellow - purple - orange - [Tolerance]. 47k resistor color code 5 band is resistor 15k - purple - black - red - [Tolerance].

4.7k ohm resistor color code 4 band is yellow - purple - red - [Tolerance]. 4.7 k resistor color code 5 bands is yellow - purple - black - brown - [Tolerance]. 50 ohm resistor color resistor 15k is Brown - Red - Orange - [Tolerance] 500 ohm resistor color code is Green - Brown - Brown - resistor 15k 500 ohm resistor is a nonstandard value of resistor, so use the 510 ohm resistor color code instead.) 5.6k resistor color code (also 5k6 ohm resistor color code) is Green - Blue - Red - [Tolerance].

6k8 ohm resistor color code (namely 6.8 k resistor color code) is Blue - Gray - Red - [Tolerance]. 1.How do you calculate resistor color code? Hold the resistor with the gold or silver band to the right and read the color resistor 15k from the left to the right. Select the color codes from the bands on the resistor.

Read the colors from left to right. The resistance value based on the color code provided is now displayed. 3.How do I know if I have a 100K resistor? 100k ohm resistor color code- 4 band 1) Brown, Black, Yellow, Gold. 2) And tolerance considered as ==> 5% of 100K ==>5000Ω 3) Other methods: Remove the resistor from PCB then test it with a DMM in resistance mode and note down its value. It needs to be separated from pcb so as to avoid the equivalent parallel resistance from resistors in the circuit.

8.What is resistor explain? A passive electrical component with two terminals that are used for either limiting or regulating the flow of electric current in electrical circuits.

The main purpose of the resistor is to reduce the current flow and to lower the voltage in any particular portion of the circuit. 9. What is 2.2k ohm Resistor color code for 4-band? The color code of 2.2 k resistor is Red-Red-Red-Gold. From the above resistor color code table, you will find that Red stands for 2 and Red for 2.

The third band is Red, so it means a multiplier value of 2 (100). And the 4th band is Gold, which means the resistor 15k is 5%. Thus the value of 2k2 resistor is 56 · 102 = 56 · 100 = 5600 Ω.

Thus The resistance value lies therefore between 5320 and 5880 Ω (5560 ± 5%). 10.How do I know if I have a 10k ohm resistor? You could read its band color and get it with the online color code calculator. For example, the 4 band 10k resistor color code is brown-black-orange-silver/gold. And the tolerance of the silver band is 10% or gold for 5% tolerance.

And if it is a 5 band resistor, the 10k resistor color code will be brown-black-black-red. Resistor 15k the tolerance band is separated from the other 4 bands color code. Its color could be one of several depending on the resistors tolerance. 12. I have a resistor with only 3 bands, How to know its value?

3-band resistors have a tolerance of 20% and are widely employed by amateurs or in situations where the resistance value is not crucial. Brown, black, and gold are the colors for a 3 band 1R0 (1 ) resistor. Between 1.2 and 0.8 will be the resistance value. Therefore, you don't need to enter the 4th band while using our online resistor color code calculator. Because there is not a tolerance ring for 20% resistors.

However, the 3 band resistor will be calculated through the 4 bands color code rule (digit, digit, multiplier).Therefore, the 4 band resitor color code calculator is 3 band resistor color code calculator too. For example: 3 band resistor color code of a 10K resistor with 20% tolerance is Brown, black, orange. Resistor color code 3 band for 220 ohm resistors with 20% tolerance is Red, red, brown.

13. Which is the first band for the colored-resistors? There are a few guidelines to follow: 1.) The color bands on certain resistors are packed together and/or near to one end.

Hold the resistor to the left of the tightly clustered bars and read the resistor from left to right. 2.) The process for reading 5% and 10% resistors is straightforward: hold the resistor with the silver or gold band to the right and read the resistance from left to right. 3.) The resistor 15k band can't be silver or gold, so if you have one, you'll know where to start right away. As fundamental resistor values vary from 0.1 Ohm to 10 Mohms, the third color for 4-band resistors will resistor 15k blue (106) or less, while the fourth color for 5-band resistors will be green (105) or less.

14. How do you read a 3-band resistor? For a 3-band resistor color codes, the first two bands always denote the first two digits of the resistance value while the third band represents the multiplier.

In the example we have, the bands are brown, black and brown. The first band is the brown band closest to the edge. Utmel uses cookies to help deliver resistor 15k better online experience. You can see what cookies we serve and how to set your preferences in our Cookies Policy, if you agree on our use of cookies please click continue.

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CONTINUE

Thermistors can be used to produce an analogue output voltage with variations in ambient temperature and as such can be referred to as a transducer. This is because it creates a resistor 15k in its electrical properties due to an external and physical change in heat. The thermistor is basically a two-terminal solid state thermally sensitive transducer constructed using sensitive semiconductor based metal oxides with metallised or sintered connecting leads formed into a ceramic disc or bead.

This allows the thermistor to change its resistive value in proportion to small changes in ambient temperature. In other words, as its temperature changes, so too does its resistance and as such its name, “Thermistor” is a combination of the words THERM-ally sensitive res-ISTOR.

While the change in resistance due to heat is generally undesirable in standard resistors, this effect can be put to good use in many temperature detection circuits. Thus being a non-linear variable-resistive devices, thermistors are commonly used as temperature sensors having many applications to measure the temperature of both liquids and ambient air. Also, being a solid state resistor 15k made from highly sensitive metal oxides, they operate at the molecular level with the outermost (valence) electrons becoming more active producing a negative temperature coefficient, or less active producing a positive resistor 15k coefficient as the temperature of the thermistor is increased.

This means they have very good resistance verses temperature characteristics allowing them to operate at temperatures upto 200 oC. Typical Thermistor While the principle use of thermistors are as resistive temperature sensors, they can also be connected in series with another component or device to control an electrical current flowing through them. In other words, they can be used as a thermally sensitive current-limiting devices. Thermistors are available in a whole range of types, materials and sizes characterised by their response time and operating temperature.

Also, hermetically sealed thermistors eliminate errors in resistance readings due to moisture penetration while still offering high operating temperatures and a compact size. The three most common types are: Bead thermistors, Disk thermistors, and Glass encapsulated thermistors. These heat-dependent resistors can operate in one of two ways, either by increasing or decreasing their resistive value with changes in temperature. Then there are two types of thermistors available: negative temperature coefficient (NTC) of resistance and positive temperature coefficient (PTC) of resistance.

Negative Temperature Coefficient Thermistor Negative temperature coefficient of resistance thermistors, or NTC thermistors for short, reduce or decrease their resistive value as the operating temperature around them increases.

Generally, NTC thermistors are the most commonly used type of temperature sensors as they can be used in virtually any type of equipment where temperature plays a role. NTC temperature thermistors have a negative electrical resistance versus temperature (R/T) relationship.

The relatively large negative response of an NTC thermistor means that even small changes in temperature can cause significant changes in their electrical resistance.

This makes them ideal for accurate temperature measurement and control. We said previously that a thermistor is an electronic component whose resistance is highly dependent on temperature so if we send a constant current through the thermistor and then resistor 15k the voltage drop across it, we can thus determine its resistance at a particular temperature. An NTC thermistors reduces its resistance with an increase in temperature and are available in a variety of base resistances and temperature curves.

NTC thermistors are usually resistor 15k by their base resistance resistor 15k room temperature, that is 25 oC, (77 oF) as this provides a convenient reference point. So for example, 2k2Ω at 25 oC, 10kΩ at 25 oC or 47kΩ at 25 oC, etc. Another important characteristic of a thermistor is its “B” value.

The B value is a material constant which is determined by the ceramic material from which it is made. it describes the gradient of the resistive (R/T) curve over a particular temperature range between two temperature resistor 15k. Each thermistor material will have a different material constant and therefore a different resistance versus temperature curve. Thus the B value will define the thermistors resistive value at a first temperature or resistor 15k point, (which is usually 25 oC), called T 1, and the thermistors resistive value at a second temperature point, for example 100 oC, called T 2.

Therefore the B value will define the thermistors material constant between the range of T 1 and T 2. That is B T1/T2 or B 25/100 with typical NTC thermistor B values given anywhere between about 3000 and about 5000.

Note however, resistor 15k both the temperature points of T 1 and T 2 are calculated in the temperature units of Kelvin where 0 0C = 273.15 Kelvin. Thus a value of 25 oC is equal to 25 o + 273.15 = 298.15K, and 100 oC is equal to 100 o + 273.15 = 373.15K, etc. So by knowing the B value of a particular thermistor (obtained from manufacturers datasheet), it is possible to produce a table of temperature versus resistance to construct a suitable graph using the following normalised equation: Thermistor Equation • Where: • T 1 is the first temperature point in Kelvin • T 2 is the second temperature point in Kelvin • R 1 is the thermistors resistance at temperature T1 in Ohms • R 2 is the thermistors resistance at temperature T2 in Ohms Thermistor Example No1 A 10kΩ NTC thermistor has a “B” value of 3455 between the temperature range of 25 oC and 100 oC.

Calculate its resistive value at 25 oC and again at 100 resistor 15k. Data given: B = 3455, R1 = 10kΩ at 25 o. In order to convert the temperature scale from degrees Celsius, oC to degrees Kelvin add the mathematical constant 273.15 The value of R1 is already given as 10kΩ base resistance, thus the value of R2 at 100 oC is calculated as: Giving the following two point characteristics graph of: Note that in this simple example, only two points were found, but generally thermistors change their resistance exponentially with changes in temperature so their characteristic curve is nonlinear, therefore the more temperature points are calculated the more accurate will be the curve.

Temperature ( oC) 10 20 25 30 40 50 60 70 80 90 100 110 120 Resistance (Ω) 18476 12185 10000 8260 5740 4080 2960 2188 1645 1257 973 765 608 and these points can be plotted as shown to give a more accurate characteristics curve for the 10kΩ NTC Thermistor which has a B-value of 3455. NTC Thermistor Characteristics Curve Notice that it has a negative temperature coefficient (NTC), that is its resistance decreases with increasing temperatures. Using a Thermistor to Measure Temperature. So how can we use a thermistor to measure temperature.

Hopefully by now we realise that a thermistor is resistor 15k resistive device and therefore according to Ohms law, if we pass a current through it, a voltage drop will be produced across it.

As a thermistor is an passive type of a sensor, that is, it requires an excitation signal for its operation, any changes in its resistance as a result of changes in temperature can be converted into a voltage change. The simplest way of doing this is to use the thermistor as part of a potential divider circuit as shown. A constant supply voltage is applied across the resistor and thermistor series circuit with the output voltage measured from across the thermistor.

If for example we use a 10kΩ thermistor with a series resistor of 10kΩ, then the output voltage at the base temperature of 25 oC will be half the supply voltage as 10Ω/(10Ω+10Ω) = 0.5. When the resistance of the thermistor changes due to changes in temperature, the fraction of the supply voltage across the thermistor will also change producing an output voltage which is proportional to the fraction of the total series resistance between the output terminals.

Thus the potential divider circuit is an example of a simple resistance to voltage converter where the resistance of the thermistor is controlled by temperature with the output voltage produced being proportional to the temperature.

So the hotter the thermistor gets, the lower the ouput voltage. If we reversed the positions of the series resistor, R S and the thermistor, R TH, then the output voltage would resistor 15k in the opposite direction, resistor 15k is the hotter the thermistor gets, the higher the output voltage.

We can use NTC thermistors resistor 15k part of a basic temperature sensing configuration using a bridge circuit as shown. The relationship between resistors R 1 and Resistor 15k 2 sets the reference voltage, V REF to the value required. For example, if both R 1 and R 2 are of the same resistive value, the reference voltage will be equal to half of the supply voltage as before.

That is Vs/2. As the temperature and therefore the resistive value of the thermistor changes, the voltage at V TH will also change, either higher or lower than that at V REF producing a positive or negative output signal to the connected amplifier. The amplifier circuit used for this basic temperature sensing bridge circuit could act as a differential amplifier for high sensitivity and amplification, or a simple Schmitt-trigger circuit for ON-OFF switching.

The problem with passing a current through a thermistor in this way, is that thermistors experience what is called a self-heating effect, that is the I 2*R power loss could be high enough to create more heat than can be dissipated by the thermistor affecting its resistive value producing false results.

Thus it is possible that if the current through the thermistor is too high it would result in increased power dissipation and as the temperature increases, its resistance decreases causing more current to flow, which increases the temperature further resulting in what is known as Thermal Runaway. In other words, we want the thermistor to be hot due to the external temperature being measured and not by itself heating up.

The value for the series resistor, R S above should be chosen to provide a reasonably wide response over the expected range of temperatures for which the thermistor is likely to be used while at the same time limiting the current to a safe value at the highest temperature.

One way of improving on this and having a more accurate conversion of resistance against temperature (R/T) is by driving the thermistor with a constant current source.

The change in resistance can be measured by using a small and measured direct current, or DC, passed through the thermistor in order to measure the output voltage drop produced. Thermistor Used For Inrush Current Suppression We resistor 15k seen here resistor 15k thermistors are used as resistive temperature sensitive transducers, but the resistance of a thermistor can be changed either by external temperature changes or by changes in temperature caused by an electrical current flowing through them, as after all, they are resistive devices. Ohm’s Law tells us that when an electrical current passes through a resistance R, as a result of the applied voltage, power is consumed in the form of heat due to the I 2*R heating effect.

Because of the self-heating effect of current in a thermistor, a thermistor can change its resistance with changes in current. Inductive electrical equipment such as motors, transformers, ballast lighting, etc, suffer from excessive inrush currents when they are first turned “ON”.

But series connected thermistors can also be used to resistor 15k limit any high initial currents to a safe value. NTC thermistors with low values of cold resistance (at 25 oC) are generally used for such current regulation. Inrush Resistor 15k Limiting Thermistor Inrush current suppressors and surge limiters are types of series connected thermistor whose resistance drops to a very low value as it is heated by the load current passing through it. At the initial turn-on, the thermistors cold resistance value (its base resistance) is fairly high controlling the initial inrush current to the load.

As a result of the load current, the thermistor heats up and reduces its resistance relatively slowly to the point were the power dissipated across it is sufficient to maintain its low resistance value with most of the applied voltage developed across the load. Due to the thermal inertia of its mass, this heating effect takes a few seconds during which the load current increases gradually rather than instantaneously, so any high inrush current is restricted and the power it draws reduces accordingly. Because of this thermal action, inrush current suppression thermistors can therefore operate very hot in their low-resistive state. As such require a cool-down or recovery period once power is removed thus allowing the resistance of the NTC thermistor to recover sufficiently ready for the next time it is needed. The speed of response of a current limiting thermistor is given by its time constant.

That is, the time taken for its resistance to change by by 63% (i.e. 1 to 1/ε) of the total change. For example, suppose the ambient temperature changes from 0 to 100 oC, then the 63% time constant would be the time taken for the thermistor to have a resistive value at 63 oC.

NTC thermistors provide protection from undesirably high inrush currents, while their resistance remains negligibly low during continuous operation supplying power to the load. The advantage here is that they able to effectively handle much higher inrush currents than standard fixed current limiting resistors with the same power consumption. Thermistor Summary We have seen here in this tutorial about thermistors, that a thermistor is a two terminal resistive transducer which can change its resistive value with changes in the surrounding ambient temperature, hence the name thermal-resistor, or simply “thermistor”.

Thermistors are inexpensive, easily-obtainable temperature sensors constructed using semiconductor metal oxides. They are available with either a negative temperature coefficient, (NTC) of resistance or a positive temperature coefficient (PTC) of resistance. The difference being that NTC thermistors reduce their resistance as the temperature increases, while PTC thermistors increase their resistance as the temperature increases.

NTC thermistors are the most commonly used (especially the 10KΩ NTC thermistor) and along with an addition series resistor, R S can be used as part of a simple resistor 15k divider circuit. Thus changes to its resistance due to changes in temperature, produces a temperature-related output voltage. However, the operating current of the thermistor must be kept as low as possible to reduce any self-heating resistor 15k.

If their operating current is too high, they can heat up quicker than they can be dissipate it, creating false results. Thermistors are characterised by their base resistance as well as their “B” value. The base resistance, for example, 10kΩ, is the resistance of the thermistor at a given temperature, usually 25 oC so is defined as: R 25.

The B value is a fixed material constant that describes resistor 15k shape of the slope of the resistive curve over temperature (R/T). We have also seen that as well as being used to measure an external temperature, thermistors can also be used to control an electrical current as resistor 15k result of the I 2R heating effect caused by the current flowing through it.

By connecting an NTC thermistor in series with a load, it is possible to effectively limit any high inrush currents. I am curious about the installation when using a thermistor to measure (sense) room temperature remotely for an air conditioner thermostat. If the wiring attached to the thermistor is inside a high temperature cavity, whereby the wiring is heated to resistor 15k half an inch from the thermistor, wouldn’t the thermister pick up that heat and give a false room-temperature reading?

I believe that’s what is happening in my RV with the thermistors mounted in the headliner. The thermistor is on the room side of the headliner, but within half and inch of it, the wiring is sitting in a cavity heated by the roof panel in the sun.

Thank you for any and all comments. Joe Bottieri A thermistor is basically a solid-state variable resistor that changes its resistive value with a change in ambient temperature, hence its name. Most thermistors have a negative temperature coefficient (NTC), which means its resistance decreases with increasing temperature (PTC’s types are also available).

A standard thermistor could have a resistive value of 10kΩ at 25 oC and a non-linear range from 1000’s of ohms at minus temperatures to 10’s of ohms at very high temperatures. So as the resistance of any connecting wires would be much less than 1Ω per length, they would have negligable effect on its response. Being a resistive device, thermistors require bridge circuits or resistive networks, as well as a power supply to operate, so it is more probable that you are using the wrong type of thermistor, or your circuit/application requires calibrating.

Thank you for the response it is very much appreciated. My concern is the heat transfer from the metal wires connected to the thermistor not the resistance in the length of the wires. What I mean is the thermistor is on the underside of the ceiling panel and the wires connected to it are in the very hot air space above, not more than 1/2 inch from the head of the thermistor.

It seems to me that considerable heat is being conducted to the the thermistor from the wires and additionally; the ceiling panel itself is very warm, which is what the thermistor is attached to. It doesn’t seem possible the thermistor could ignore all that and react only to the air temperature in the room. Que tal Joe Bottieri, de ser posible podrías emplear el termómetro de tu multímetro para revisar ambas temperaturas, donde se localiza el termistor y los cables, revisar a que resistencia cambia con esas temperaturas y definir si esto le esta afectando.

De ser así, te recomiendo que hagas un ajuste en la calibración o resistor 15k compensación midiendo esa temperatura mas alta o colocar algún tipo de recubrimiento térmico para esos cables y evitar que se vean afectados. Existen aislantes de cable de fibra de vidrio (usados en instalaciones de hornos y quemadores) o también hay cintas que evitan la transferencia térmica.

In Samsung refrigerator, I found it over cooling in the fridge compartment so that the vegetable in drawer being iced, I think this is because the ambient thermistor getting older and can not reach high resistance as expected (to say: 13k ohms at 0 degree C.

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But opting out of some of these cookies may affect your browsing experience. Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously. Cookie Duration Description cookielawinfo-checkbox-analytics 11 months This cookie is set by GDPR Cookie Consent plugin.

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viewed_cookie_policy 11 months The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.Thermistors/Temperature Measurement with NTC Thermistors By Philip Kane Thermistors (thermal resistors) are temperature dependent variable resistors.

There are two types of thermistors, Positive Temperature Coefficient (PTC) and Negative Temperature Coefficient (NTC). When the temperature increases, PTC thermistor resistance will increase and NTC thermistor resistance will decrease.

They exhibit the opposite response when the temperature decreases. Both types of thermistors are used in a variety of application areas. However, here the focus will be on using NTC resistor 15k to measure temperature in microcontroller based applications. Thermistor Specifications The following NTC thermistor parameters can be found in the manufacturer's data sheet. • Resistance This is the thermistor resistance at the temperature specified by the manufacturer, often 25°C.

• Tolerance Indicates how much the resistance can vary from the specified value. Usually expressed in percent (e.g. 1%, 10%, etc). For example, if the specified resistance at 25°C for a thermistor with 10% tolerance is 10,000 ohms then the measured resistance at that temperature can range from 9,000 ohms to 11000 ohms. • B (or Beta) constant A value that represents the relationship between the resistance and temperature over a specified temperature range.

For example, "3380 25/50" indicates a beta constant of 3380 over a temperature range from 25°C to 50°C. • Tolerance on Beta constants Beta constant tolerance in percent. • Operating Temperature Range Minimum and maximum thermistor operating temperature. • Thermal Time Constant When the temperature changes, the time it takes to reach 63% of the difference between the old and new temperatures. • Thermal Dissipation Constant Thermistors are subject to self-heating as they pass current.

This is the amount of power required to raise the thermistor temperature by 1°C. It is specified in milliwatts per degree centigrade (mW/°C). Normally, power dissipation should be kept low to prevent self-heating. • Maximum Resistor 15k Power Maximum power dissipation. It is specified in Watts (W). Exceeding this specification will cause damage to the thermistor. • Resistance Temperature Table Table of resistance values and associated temperatures over the thermistors operating temperature range.

Thermistors operate over a relatively limited temperature range, typically -50 to 300°C depending on type of construction and coating. Thermistor Response to Temperature As with any resistor, you can use the ohmmeter setting on your multimeter to measure thermistor resistance.

The resistance value displayed on your multimeter should correspond to the ambient temperature near the thermistor. The resistance will change in response to temperature change. Part List Full kit with Arduino Qty. Description Mfr. Part No. 1 MCU, Arduino Uno R3 A000066 1 28AWG Shielded USB Cable 10U2-02206W 1 Thermistor 10kΩ NTC-103-R 10 Resistor Carbon Film 10kΩ CF1/4W103JRC 1 Breadboard 170 points 1.9" x 1.3" WBP-317 1 Jumper Wire Male to Male, 10-pack WJW004 1 9V Battery Snap 1X9V-2.1 SNAP 1 9V Alkaline Battery ALK 9V 522 Figure 1: Thermistor resistance changes with temperature.

Figure 2 shows the response of a NTC thermistor between -40°C and 60°C. From the figure you can see that thermistors have high sensitivity. A small change in temperature causes a large change in resistance. Also note that the response of this thermistor is not linear. That is, the change in resistance for a given change in temperature is not constant over the thermistor's temperature range.

Figure 2: Thermistor temperature-resistance curve -40°C to 60°C The manufacturer's data sheet includes a list of thermistor resistance values and corresponding temperatures over its range. One solution for dealing with this non-linear response is to include a look-up table containing this temperature-resistance data in your code. After calculating the resistance (to be described later) your code searches the table for the corresponding temperature.

Linearizing Thermistor Response On the hardware side you can linearize thermistor response by placing a fixed resistor in parallel or in series with it.

This improvement will come at the cost of some accuracy. The value of the resistor should be equal to the thermistor resistance at the midpoint of the temperature range of interest. Thermistor – parallel resistor combination Figure 3 shows the S shaped temperature-resistance curve produced by placing a 10K resistor in parallel with a thermistor whose resistance is 10K at 25°C. This makes the region of the curve between 0°C and 50°C fairly linear. Note that maximum linearity is around the midpoint, which is at 25°C.

Figure 3: Temperature-resistance curve of thermistor and parallel resistor combination. Thermistor - series resistor combination (voltage divider) A common way resistor 15k microcontrollers to capture analog data is via an analog to digital converter (ADC).

You can't directly read the thermistors resistance with an ADC. The resistor 15k thermistor-resistor combination, shown in figure 4, resistor 15k a simple solution in the form resistor 15k a voltage divider. Figure 4: Thermistor voltage divider. You use the following formula to calculate the voltage divider output voltage: Vo = Vs * (R0 / ( Rt + R0 )) The linearized temperature-voltage curve in figure 5 shows the change in voltage divider output voltage Vo in response to temperature change.

The source voltage Vs is 5 volts, the thermistor resistance Rt is 10K ohms at 25°C, and series resistor R0 is 10K ohms. Similar to the parallel resistor-thermistor combination above, this combination has maximum linearity around the mid point of the curve, which is at 25°C.

Figure 5: Temperature-voltage curve. Note that, since Vs and R0 are constant, the output voltage is determined by Rt. In other words, the voltage divider converts thermistor resistance (and thus temperature) to voltage. Perfect for input to a microcontroller ADC. Converting ADC Data to Temperature by first finding the thermistor resistance To convert ADC data to temperature you first find the thermistor resistance and then use it to find the temperature. You can rearrange the above voltage divider equation to solve for the thermistor resistance Rt: Rt = R0 * (( Vs / Vo ) - 1) If the ADC reference voltage (Vref) and voltage divider source voltage (Vs) are the same then the following is true: adcMax resistor 15k adcVal = Vs / Vo That is, the ratio of voltage divider input voltage to output voltage is the same as the ratio of the ADC full range value (adcMax) to the value returned by the ADC (adcVal).

If you are using a 10 bit ADC then adcMax is 1023. Figure 6: Voltage divider circuit and ADC with common reference voltage.

Now you can replace the ratio of voltages with the ratio of ADC values in the equation to solve for Rt: Rt = R0 * ((adcMax / adcVal) - 1) For example, assume a thermistor with a resistance of 10K ohms at 25°C, a 10 bit ADC, and adcVal = 366.

Rt = 10,000 * ((1023 / 366) – 1) = 10,000 * (2.03) = 17,951 ohms Once you calculate the value for Rt, you can use a look-up table containing temperature-resistance data for your thermistor to find the corresponding temperature.

The calculated resistance for the thermistor in the above example corresponds to a temperature of approximately 10°C. 9 18,670 10 17,926 11 17,214 The manufacturer's data sheet might not include all temperature-resistance values for the thermistor or you might not have sufficient memory to include all of the values in your look-up table. In either case you will need to include code to interpolate between the listed values.

By Calculating The Temperature Directly Alternatively, you can use an equation that approximates the thermistors temperature response curve to calculate the temperature. For example, the widely used Steinhart-Hart equation shown below. It is not as exact as the manufacturer's resistance-temperature data.

However, compared to other methods, it provides a much closer approximation of the thermistor's response curve over its operational range. 1/T = A + B*ln(R) + C*(ln(R))^3 The manufacturer may or may not supply values for the coefficients A, B, and C.

If not, they can be derived using measured temperature-resistance data. However, that is beyond the scope of this article. Instead, we will use the simpler Beta (or B) parameter equation shown below. Though not as accurate as the Steinhart-Hart equation, it still provides good results over a narrower temperature range. 1/T = 1/T0 + 1/B * ln(R/R0) The variable T is the ambient temperature in Kelvin, T0 is usually room temperature, also in Kelvin (25°C = 298.15K), B is the beta constant, R is the thermistor resistance resistor 15k the ambient temperature (same as Rt above), and R0 is the thermistor resistance at temperature T0.

The values for T0, B, and R0 can be found in the manufacturer's data sheet. You can calculate the value for R as described previously for Rt. If the voltage divider source voltage and Vref are the same you don't need to know R0 or find R to calculate the temperature. Remember you can write the equation for the thermistor resistance in terms of the ratio of ADC values: R = R0 * ( ( adcMax / adcVal ) - 1 ) then: 1/T = 1/T0 + 1/B * ln( R0 * ( ( adcMax / adcVal ) - 1 ) / R0 ) R0 cancels out, which leaves: 1/T = 1/T0 + 1/B * ln( ( adcMax / adcVal ) – 1 ) Take the reciprocal of the result to get the temperature in Kelvin.

For example, assume a thermistor voltage divider circuit is connected to a 10 bit ADC. The beta constant for the thermistor is 3380, the thermistor resistance (R0) at 25°C is 10K ohms, and the ADC returns a value 366. 1/T = 1/298.15 + 1/3380 * ln((1023 / 366) - 1 ) 1/T = 0.003527 T = 283.52K – 273.15K = 10.37°C Example: A Simple Arduino Based Temperature Logger Figure 7 shows a simple temperature logger consisting of an Arduino Uno SBC and a thermistor voltage divider (right).

The voltage divider output is connected to Arduino's internal 10 bit ADC via one of the analog pins. The Arduino gets the ADC value, calculates the temperature, and sends it to the serial monitor for display. Figure 7: Arduino temperature logger circuit.

The following Arduino sketch uses the B parameter equation to calculate the temperature. The function getTemp does most of the work. It reads the analog pin multiple times and averages the ADC values. It then calculates the temperature in Kelvin, converts it to Celsius and Fahrenheit and returns all three values to the main loop. The main loop repeatedly calls getTemp, with a 2 second delay between calls.

It sends the temperature values returned by getTemp to the serial monitor. Figure 8: Screenshot of temperature logger output.

Download example code here. void getTemp(float * t) { // Converts input from a thermistor voltage divider to a temperature value. // The voltage divider consists of thermistor Rt and series resistor R0. // The value of R0 is equal to the thermistor resistance at T0. // You must set the following constants: // adcMax ( ADC full range value ) // analogPin (Arduino analog input pin) // invBeta (inverse of the thermistor Beta value supplied by manufacturer).

// Use Arduino's default reference voltage (5V or 3.3V) with this module. // const int analogPin = 0; // replace 0 with analog pin const float invBeta = 1.00 / 3380.00; // replace "Beta" with beta of thermistor const float adcMax = 1023.00; const float invT0 = 1.00 / 298.15; // room temp in Kelvin int adcVal, i, numSamples = 5; float K, C, F; resistor 15k = 0; for (i = 0; i < numSamples; i++) { adcVal = adcVal + analogRead(analogPin); delay(100); } adcVal = adcVal/5; K = 1.00 / (invT0 + invBeta*(log ( adcMax / (float) adcVal - 1.00))); C = K - 273.15; // convert to Celsius F = ((9.0*C)/5.00) + 32.00; // convert to Fahrenheit t = K; t = C; t = F; return; } void setup() { analogReference(DEFAULT); Serial.begin(9600); } void loop() { float temp; getTemp(temp); Serial.print("Temperature is "); Serial.print(temp); Serial.print(" Kelvin "); Serial.print(temp); Serial.print(" deg.

C "); Serial.print(temp); Serial.print(" deg. F "); Serial.println(); delay(2000); return; } Measurement Error and ADC Resolution There are a number of factors that can contribute to measurement error. For example, the thermistor and series resistors may vary from their rated values (within specified tolerance limits) or there can be error due to thermistor self-heating or a noisy electrical environment can result in fluctuations in input to the ADC.

Below are a few suggestions for reducing measurement error. This assumes you are using the B parameter equation. • Measure series resistor (R) to get the actual resistance and use that value in your temperature calculation. • Similarly, if possible, measure the actual resistance (R0) for your thermistor at T0 and use that value in your calculations.

You will need an accurate thermometer, an accurate resistance meter and a way to produce the desired temperature. • Alternatively, you can select a thermistor and a resistor with tighter tolerances to reduce the error to a level acceptable for your application.

• It turns out that the Beta constant isn't really constant. The value depends on temperature and, as mentioned earlier, is usually given for a specified temperature range. If you can get accurate thermistor resistance values at two temperatures in the range of interest (preferably at the endpoints) you can use the following formula  to find the actual beta constant for your thermistor. B = ln(R1/R2) * (t1*t2)/(t2-t1) • Keep power dissipation as low as possible to avoid error due to self-heating. • Take a number of successive ADC readings and use the average of these readings in your temperature calculation. • Use a filtered voltage source for Vref.

ADC Resolution At best, the temperature in the above example is accurate to the nearest .1°C. This is because of the limitation due to ADC resolution. The ADC is not sensitive to voltage changes between steps. For a 10 bit ADC the smallest resistor 15k change that can be measured is Vref/1023.

This is the voltage resolution of the ADC. If Vref is 5V the voltage resolution is 4.89 mV. Assuming T0 is resistor 15k the smallest temperature change that can be detected at 25°C is ±0.1°C. This is the temperature resolution at 25°C. What this means is that a change in the least significant bit will cause the displayed temperature to jump by 0.1°C.

This jump is due to ADC resolution not measurement error. ADC Output Temp 511 512 513 0111111111 1000000000 1000000001 24.95°C 25.05°C 25.15°C If you need better resolution there are techniques (e.g. oversampling ) that you can use to increase the effective resolution of your microcontroller's ADC or you can use an external ADC with higher resolution.

References • AVR121: Enhancing ADC Resolution by Oversampling http://www.atmel.com/Images/doc8003.pdf • How To Find An Expression For Beta http://www.zen22142.zen.co.uk/ronj/tyf.html • Temperature Measurement with a Thermistor and an Arduino http://web.cecs.pdx.edu/~eas199/B/howto/thermistorArduino/thermistorArduino.pdf • Thermistor https://en.wikipedia.org/wiki/Thermistor • Thermistor Tutorial http://www.radio-electronics.com/info/data/resistor/thermistor/thermistor.php resistor 15k Understanding and Resistor 15k ADC Conversion Errors http://www.st.com/content/ccc/resource/technical/document/application_note/9d/56/66/74/4e/97/48/93/CD00004444.pdf/files/CD00004444.pdf/jcr:content/translations/en.CD00004444.pdf If you resistor 15k an electronics story you'd like to share, please send it to [email protected].

For almost two decades, Phil Kane has been a technical writer in the software industry and occasionally authored articles for electronics enthusiast magazines. He has a bachelor's in Electronics Engineering Technology with a minor in Computer Science. Phil has had a life-long interest in science, electronics and space exploration. He enjoys designing and building electronic gadgets, and would very much like to see at least one of those gadgets on its way to the moon or Mars one day.
• Pages in Chapter 8 • What is a Meter?

• Voltmeter Design • Voltmeter Impact on Measured Circuit • Ammeter Design • Ammeter Impact on Measured Circuit • Ohmmeter Design • High Voltage Ohmmeters • Multimeters • Kelvin (4-wire) Resistance Measurement • Bridge Circuits • Wattmeter Design • Creating Custom Calibration Resistances Ammeters Measure Electrical Current A meter designed to measure electrical current is popularly called an “ ammeter” because the unit of measurement is “amps.” In ammeter designs, external resistors added to extend the usable range of the movement are connected in parallel with the movement rather than in series as is the case for voltmeters.

This is because we want to divide the measured current, not the measured voltage, going to the movement, and because current divider circuits are always formed by parallel resistances. Designing an Ammeter Taking the same meter movement as the voltmeter example, we can see that it would make a very limited instrument by itself, full-scale deflection occurring at only 1 mA: As is the case with extending a meter movement’s voltage-measuring ability, we would have to correspondingly re-label the movement’s scale so that it read differently for an resistor 15k current range.

For example, if we wanted to design an ammeter to have a full-scale range of 5 amps using the same meter movement as before (having an intrinsic full-scale range of only 1 mA), we would resistor 15k to re-label the movement’s scale to read 0 A on the far left and 5 A on the far right, rather than 0 mA to 1 mA as before. Whatever extended range provided by the parallel-connected resistors, we would have to represent graphically on the meter movement face.

Using 5 amps as an extended range for our sample movement, let’s determine the amount of parallel resistance necessary to “shunt,” or bypass, the majority of current so that only 1 mA will go through the movement with a total current of 5 A: From our given values of movement current, movement resistance, and total circuit (measured) current, we can determine the voltage across the meter movement ( Ohm’s Law applied to the center column, E=IR): Knowing that the circuit formed by the movement and the shunt is of a parallel configuration, we know that the voltage across the movement, shunt, and test leads (total) must be the same: We also know that the current through the shunt must be the difference between the total current (5 amps) and the current through the movement (1 mA), because branch currents add in a parallel configuration: Then, using Ohm’s Law (R=E/I) in the right column, we can determine the necessary shunt resistance: Of course, we could have calculated the same value of just over 100 milli-ohms (100 mΩ) for the shunt by calculating total resistance (R=E/I; 0.5 volts/5 amps = 100 mΩ exactly), then working the parallel resistance formula backwards, but the arithmetic would have been more challenging: An Ammeter in Real-Life Designs In real life, the shunt resistor of an ammeter will usually be encased within the protective metal housing of the meter unit, hidden from sight.

Note the construction of the ammeter resistor 15k the following photograph: This particular ammeter is an automotive unit manufactured by Stewart-Warner. Although the D’Arsonval meter movement itself probably has a full scale rating in the range of milliamps, the meter as a whole has a range of +/- 60 amps. The shunt resistor providing this high current range is enclosed within the metal housing of the meter.

Note also with this particular meter that the needle centers at zero amps and can indicate either a “positive” current or a “negative” current.

Connected to the battery charging circuit of an automobile, this meter resistor 15k able to indicate a charging condition (current flowing from generator to battery) or a discharging condition (current flowing from battery to the rest of the car’s loads). Increasing an Ammeter’s Usable Range As is the case with multiple-range voltmeters, ammeters can be given more than one usable range by incorporating several shunt resistors switched with a multi-pole switch: Notice that the range resistors are connected through the switch so as to be in parallel with the meter movement, rather than in series as it was in the voltmeter design.

The five-position switch makes contact with only one resistor at a time, of course. Each resistor is sized accordingly for a different full-scale range, based on the particular rating of the meter movement (1 mA, 500 Ω). Resistor 15k such a meter design, each resistor value is determined by the same technique, using a known total current, movement full-scale deflection rating, and movement resistance. For an ammeter with ranges of 100 mA, 1 A, 10 A, and 100 A, the shunt resistances would be as such: Notice that these shunt resistor values are very low!

5.00005 mΩ is 5.00005 milli-ohms, or 0.00500005 ohms! To achieve these low resistances, ammeter shunt resistors often have to be custom-made from relatively large-diameter wire or solid pieces of metal. One thing to be aware of when sizing ammeter shunt resistors is the factor of power dissipation.

Unlike the voltmeter, an ammeter’s range resistors have to carry large amounts of current. If those shunt resistor 15k are not sized accordingly, they may resistor 15k and suffer damage, or at the very least lose accuracy due to overheating.

For the example meter above, the power dissipations at full-scale indication are (the double-squiggly lines represent “approximately equal to” in mathematics): An 1/8 watt resistor would work just fine for R 4, a 1/2 watt resistor would suffice for R 3 and a 5 watt for R 2 (although resistors tend to maintain their long-term accuracy better if not operated near their rated power dissipation, so you might want to over-rate resistors R 2 and R 3), but precision 50 watt resistors are rare and expensive components indeed.

A custom resistor made from metal stock or thick wire may have to be constructed for R 1 to meet both the requirements of low resistance and high power rating. Sometimes, shunt resistors are used in conjunction with voltmeters of high input resistance to measure current.

In these cases, the current through the voltmeter movement is small enough to be considered negligible, and the shunt resistance can be sized according to how many volts or millivolts of drop will be produced per amp of current: If, for example, the shunt resistor 15k in the above circuit were sized at precisely 1 Ω, there would be 1 volt dropped across it for every resistor 15k of current through it.

The voltmeter indication could then be taken as a direct indication of current through the shunt. For measuring very small currents, higher values of shunt resistance could be used to generate more voltage drop per given unit of current, thus extending the usable range of the (volt)meter down into lower amounts of current.

The use of voltmeters in conjunction with low-value shunt resistances for the measurement of current is something commonly seen in industrial applications. Using a Shunt Resistor and a Voltmeter Instead of an Ammeter The use of a shunt resistor along with a voltmeter to measure current can be a useful trick for simplifying the task of frequent current measurements in a circuit.

Normally, to measure currentthrough a circuit with an ammeter, the circuit would have to be broken (interrupted) and the ammeter inserted between the separated wire ends, like this: If we have resistor 15k circuit where current needs to be measured often, or we would just like to make the process of current measurement more convenient, a shunt resistor could be placed between resistor 15k points and left there permanently, current readings taken with a voltmeter as needed without interrupting continuity in the circuit: Of course, care must be taken in sizing the shunt resistor low enough so that it doesn’t adversely affect the circuit’s normal operation, but this is generally not difficult to do.

This technique might also be useful in computer circuit analysis, where we might want to have the computer display current through a circuit in terms of a voltage (with SPICE, this would allow us to avoid the idiosyncrasy of reading negative current values): shunt resistor example circuit v1 1 0 rshunt 1 2 1 rload 2 0 15k .dc v1 12 12 1 .print dc v(1,2) .end v1 v(1,2) 1.200E+01 7.999E-04 We would interpret the voltage reading across the shunt resistor (between circuit nodes 1 and 2 in the SPICE simulation) directly as amps, with 7.999E-04 being 0.7999 mA, or 799.9 µA. Ideally, 12 volts applied directly across 15 kΩ would give us exactly 0.8 mA, but the resistance of the shunt lessens that current just a tiny bit (as it would in real life). However, such a tiny error is generally well within acceptable limits of accuracy for either a simulation or a real circuit, and so shunt resistors can be used in resistor 15k but the most demanding applications for resistor 15k current measurement.

REVIEW: • Ammeter ranges are created by adding parallel “shunt” resistors to the movement circuit, providing a precise current division. • Shunt resistors may have high power dissipations, so be careful when choosing parts for such meters! • Shunt resistors can be used in conjunction with high-resistance voltmeters as well as low-resistance ammeter movements, producing accurate voltage drops for given amounts of current. Shunt resistors should be selected for as low a resistance value as possible to minimize their impact upon the circuit under test.

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