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Questions tagged [thermistor]

A device that is used to detect temperature - the word is a portmanteau of thermometer and resistor. The detection mechanism is the measurement of resistance which changes predictably with temperature.

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Testing Thermistors and Resistor that reads as a Capcitor

I have an Air Source Heat Pump that has stopped working, I have an error code which is: Faulty thermistor - dead short/open circuit. There are 5 thermistors in total, one built into the power board ...
Alan A's user avatar
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How to apply a thermistor to my LED driver (TLC59116 PW package)

I currently use a TLC 59116 16-channel I2C LED driver in a 4 x 4 LED array driven by Arduino and would like to add a thermistor to the circuit design. I'm unsure where to add it or what supporting ...
Mak's user avatar
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Adjusting underfloor heating thermistor resistance to match a different controller

I have DeviMat underfloor heating installed in my bathroom, presently matched to a Danfoss DeviReg "smart" thermostat. There's a matching Devi heating probe installed under the floor which I ...
Daniel Sinclair's user avatar
1 vote
2 answers
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Is it better to use a NTC or a MOSFET to limit inrush current [closed]

I need help to design a circuit to limit the inrush current to a simple motor controller for a 36 V, 250 W motor on an ebike. When turning on the battery to the controller there is a very large inrush ...
robert rj m's user avatar
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How do I properly wire an SL-510-SS pyrgeometer to measure its internal thermistor resistance?

I've acquired an SL-510-SS pyrgeometer and am having trouble wiring the internal thermistor. The manual gives the following description: The manual also provides the following diagram: I've ...
DaleCloudman's user avatar
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2 answers
85 views

Thermistor misreading

I'm currently working on a hotplate project with an ESP32, utilizing a 10k ohm NTC thermistor (B57550G1103F000) capable of measuring temperatures up to 300°C. However, I'm encountering issues with ...
Loic Daigle's user avatar
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2 answers
135 views

What's the output voltage

For the circuit shown in Fig. 3, the bridge is balanced when T=100 C. That is R1=R2=R3=R4=10k ohm. The thermistors are matched, and their resistance related to temperature by ...
user16780029's user avatar
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2 answers
62 views

Thermocouple vs NTC

I want to test the accuracy of the NTC soldered in a current sensing board with a shunt resistor. For that, I attached a thermocouple type K to the junction of the shunt using epoxy and applied a ...
404's user avatar
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3 votes
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Do I need clean Vdd when measuring resistance using ADC with Vref tied to Vdd?

I want to measure the resistance of the thermistor with the MCP3021 ADC using the voltage divider method. Since this ADC has Vref connected to Vdd and Vdd is powered from a DC/DC converter, I was ...
lekto's user avatar
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Sanity Check: Does adding a second voltage divider change the properties of the original?

I have a thermistor configured in a simple voltage divider on a 5V circuit as follows: I have no control over that part of the circuit. The problem is that, at normal operating temperatures, that ...
dave mankoff's user avatar
1 vote
1 answer
166 views

Choosing an NTC thermistor for inrush current limiting at 5 V

I'm designing a very simple circuit to enable a Raspberry Pi to power down safely in the event of a power outage. It is comprised of a supercapacitor, a diode to prevent reverse current flow, and a ...
yeah's user avatar
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2 answers
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Series resistor selection using B value

I am following this document to calculate the series resistor for an NTC. Here the NTC used is NTCG164LH223HT1.Below is the snippet from the calculation section. In the equation for RNTC the B value ...
Confused's user avatar
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3 votes
1 answer
130 views

Can the B-value for NTC be used to extrapolate beyond the B range?

Most NTC thermistors have operating range way beyond the single B value specified in the datasheet. For example NTCALUG01A473HA has operating range -40..150C but only B25/85 specified. Can I use basic ...
Maple's user avatar
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Is it possible to multiplex thermistors for multiple cell battery configurations for the BQ25756 or other JEITA charge ICs for spaced apart cells?

I'm trying to figure out how to safely implement fast charging using the BQ25756 with a most likely 2s (though up to 4s is possible) layout of physically spaced out cells. I haven't fully decided on ...
Befitting Display Name's user avatar
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Inrush current limiter thermistor acting up

One of the power amps I am working on uses a thermistor for inrush current limiting (SL15 25003) as shown in the schematic below (ICL1). When I was testing the unit it seemed to me that there was some ...
Zen Max's user avatar
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Inquiry Regarding NTC Selection and Placement for ST L6924D LiPo Battery Charger

I am planning to create a lithium-polymer (LiPo) battery charger using the ST L6924D charging IC. Could you kindly recommend an appropriate NTC (Negative Temperature Coefficient) for controlling ...
Atrahasis's user avatar
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NTC Thermistor Life span?

is there a lifespan of how long an NTC thermistor should last when used as a current inrush limiter? was thinking it should go over 10 years but not sure?
slybunda's user avatar
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How does current flow in this temperature protection circuit?

Reading through the data sheet for a TP4056 Li-ion battery charger, I found the diagram of a typical application. I'm trying to fathom how the temperature protection circuit functions. I've found this ...
nohatsatthetable's user avatar
4 votes
1 answer
235 views

Does it have to be the same thermistor?

I have two blown thermistors in a TV. I can't get the same part locally in the UK and ordering it from China will take a month at least so im looking for an alternative from local electronics parts ...
slybunda's user avatar
2 votes
2 answers
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Relay/Mosfet circuit for outputting source of highest voltage?

Currently using ntc thermistors to measure temperatures, I’m then using a comparison circuit to filter through a set of 3 thermistor-passed voltages (outputting the highest voltage).For overall design,...
lag214's user avatar
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NTC layout for MOSFET temperature sensing

Here is a picture where there is a NTC (RT501) that is surrounded by a solder ring connected to the copper pour of the drain of the MOSFETs. Any reason why the layout the way it is with the ring? Also ...
EarthLord's user avatar
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Can't get thermistor to work

I've got an NTC thermistor. This one, to be exact. It has a table of resistances corresponding to temperatures. I've used it to derive a Steinhart-Hart equation using the NTC's resistances at 0°C, 20°...
Popeye's user avatar
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1 answer
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NTC wire in a replacement LI-ion battery has a different color [closed]

I am replacing a battery pack in a speaker. It is a Li-ion 18650 2600 mAh 7.4 V. I got a replacement from a shop in China claiming to be local. The replacement has an NTC and three wires just as the ...
hk1020's user avatar
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What thermistor for a TP4056 lithium charge module?

This TP4056 Li-Ion battery charger datasheet specifies an NTC thermistor be used for battery temperature sensing while charging. Is there any further specification I should know about the NTC ...
Mark Harrison's user avatar
0 votes
4 answers
248 views

Is it better using NTC or a proper temperature sensor?

I need to sense temperature for a lithium battery pack and a TO-220 package transistor. Would an NTC with voltage divider be ok or is it better to use a sensor like the LM36? Note: Measured ...
Hazardous Voltage's user avatar
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1 answer
44 views

Maintaining Linear Temperature / Voltage-Drop Relationship Across Thermistor While Stepping Down Input Voltage

I have a 6VDC power source that is exciting an NTC Thermistor R1 (resistance of the thermistor decreases as the temperature increases, but the relationship is not linear). There is a precision ...
ferny_d's user avatar
0 votes
1 answer
647 views

What is this Component labelled VR1

My Falmec Rangehood died. It looks like a component has burst on the controller board. There is actually smoke marks on the cover of the board. It is next to F1 (non-existent), at the power entry. ...
Rohit Gupta's user avatar
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1 answer
99 views

Simulating TEC current control input for MAX1969 Peltier driver

I am trying to simulate the control loop used to drive the CTLI pin of MAX1969 shown in the figure. In this application, a DAC is used to set the temperature. I used a regular resistor to represent ...
BobaJFET's user avatar
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5 votes
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337 views

How to reverse the behavior of a thermistor?

I have an NTC thermistor that reduces its resistance when temperature increases, but I need a circuit where resistance increases. Without using a different thermistor (or a microcontroller), is there ...
Lil Mami Chula's user avatar
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1 answer
110 views

How do you turn on a NE555 Timer in general?

I have a schematic where I'm using an LM741 op-amp as a voltage comparator when its Vout is HIGH/+Vcc it "allows it to operate the 555 timer" and therefore activates the buzzer, and vice ...
geekyhez's user avatar
1 vote
1 answer
94 views

Thermal capacitance and resistance of conductive material

In my spare time I am working on this project: I have a strip of conductive fabric material wrapped around my wrist that gets hot when current flows. In addition to the measurements you follow with ...
KaleM's user avatar
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1 answer
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Adding a gauge affects the transistor switch circuit

Thanks to the help of this community I was able to build the following transistor switch circuit (details here, big thanks to @mathkeepsmebusy): The circuit works and the LED illuminates based on the ...
hezamu's user avatar
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4 votes
1 answer
173 views

I have a rechargeable battery pack that is fully charged, the batteries aren't heating up and the charge controller won't shut off. Tick, Tick, Boom?

UPDATED AGAIN Sorry folks. I kind of jumped the gun with this question. I was patient and let the charger do its thing. The voltage increase flattened out as the rate of temp change increased. The ...
Tim Cerka's user avatar
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1 answer
156 views

NTC connection and noise

I have several times used an NTC in series a resistor to sense temperature with Arduino. There can be two connections: 1) NTC between the power supply and the resistor (resistor going to ground). 2) ...
KaleM's user avatar
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0 answers
163 views

Inrush current limiting for 120V AC powered circuit

I have a load that I'm powering from a 60W AC-to-DC converter that has a stated cold start inrush current of 30A@120V: https://www.meanwellusa.com/upload/pdf/IRM-60/IRM-60-spec.pdf (the 15V output ST ...
davegravy's user avatar
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2 votes
1 answer
187 views

Does thermistor resistance vary with excitation current?

I am looking to use this thermistor for my temperature measurement application - https://media.digikey.com/pdf/Data%20Sheets/Cantherm%20PDFs/STS1_Series.pdf The spec sheet mentions that the operating ...
Tarandeep Singh Kalra's user avatar
1 vote
1 answer
88 views

How does the thermistor activate/not activate a circuit?

I have this schematic which is temperature-dependent and would only make a sound once the heat detected is above the threshold of the NTC thermistor. Can I get some help with circuit analysis? How ...
geekyhez's user avatar
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0 answers
47 views

How to choose a diode and adapt a charging circuit so it can sense temperature from two battery stacks instead of one?

I have two questions regarding the schematic below. Diode D3 (D2 in the datasheet) at location A3-A4 is not defined in the datasheet. R9 (R2 in the example) is sized at: 220Ω. The input voltage is 9V. ...
Tim Cerka's user avatar
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0 votes
2 answers
597 views

Why do we use a voltage divider to measure the voltage of a thermistor? [closed]

Can someone explain to me when and why I should use a voltage divider when I design a circuit?
Nouran's user avatar
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0 answers
67 views

Calculating thermistor value to replace fixed resistor

I have a circuit that uses a 5W 100Ω fixed resistor for inrush limiting. I'd like to replace it with a thermistor for better efficiency. I've not found any information referencing what resistance to ...
AlphaSixSierra's user avatar
8 votes
3 answers
534 views

Active thermistor giving skewed readings immediately when heating element turned on

For the purposes of experimentation and learning, I have constructed a circuit that uses a pair of 100 ohm 2 watt power resistors (in parallel for 50 ohms) to gently warm up a Microchip MCP9701A ...
Wossname's user avatar
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0 votes
2 answers
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MAX11645EUA+T ADC Readings

I am having issues with ADC readings with MAX11645EUA+T. I have a 2 input ADC and am driving the inputs with thermistors buffered each with a voltage follower. The ADC works when I have both ...
Eyurk's user avatar
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-1 votes
1 answer
159 views

Output of ADC when no input is supplied

I am working with a Raspberry Pi 3b+ connected to an MCP3008 ADC to read sensor output. When the sensor is not connected it gives some floating value (max. value). Is it possible to get a value of ...
Suvendu Sahu's user avatar
7 votes
2 answers
1k views

How serious is the 125 °C limit on an NTC thermistor?

I'm measuring a temperature for use in a thermal cutoff circuit at probably ~100 °C. Temperature exceeds 100 °C, microcontroller kills the power to it. Nothing novel here, but I'm not certain of the ...
Rgaddi's user avatar
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1 vote
1 answer
118 views

Noise on PCB trace influences NTC measurement

I have a general question regarding noise in PCB-Designs. The PCB I'm currently working on is failing some tests on the RF side. I have scanned the internet for information, but there are no concrete ...
Ben's user avatar
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4 votes
1 answer
931 views

How do I select a replacement ICL NTC thermistor for a PSU?

I want to replace an ICL (inrush current limiting) NTC thermistor in a vintage computer PSU (for Amiga 1200). This question is similar to 'Selecting an NTC for inrush current limiting', except that ...
Nick Bolton's user avatar
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0 votes
0 answers
75 views

Resistor identification on a shunt PCB of a battery manager

A battery manager (Victron Energy BMV-602S) has a shunt which has a small PCB attached to it. The manager is able to monitor two batteries - "advanced" monitoring of a leisure battery (B1) ...
Maximilian Wiens's user avatar
2 votes
3 answers
188 views

NTC resistor to balance ambient temperature change on precision current controlled lamp

I use a constant current control design to control the current through the halogen lamp, which typically runs at 800-900 mA Resistor MPN: PCS2512DR1000ET DAC: MCP4725 simulate this circuit – ...
Christianidis Vasilis's user avatar
1 vote
2 answers
171 views

Thermistor in Wheatstone configuration and ADC offset

Based on my rough analysis, I realized that by measuring a thermistor in a Wheatstone configuration, I could technically reduce the ADC offset error LSBs because we are substracting two divider ...
Cyclone1's user avatar
0 votes
3 answers
1k views

What is thermistor Beta?

In the attached datasheet, I see the Beta value (K) is from 0degC to +50degC. What does it actually signify in terms of usage in an application? Like, how to understand that parameter if I have to ...
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