analog feedback temprature regulator question - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: March 13, 2025, 10:09:42 am
content: Hello, I am looking for a differential feedback temprature regulator project which explains the theory best it could and give practical example in simulation.I am looking to design a very precise temprature regultor up to 1Kelvin.Is there some material of a project I could try to learn it?Thanks.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: March 20, 2025, 11:14:39 am
content: You can proceed with an Op-Amp (LM358), an NTC thermistor, a MOSFET (IRF540) and a resistive heater (10W).The op-amp will compare the thermistor voltage to a reference voltage. If the temperature deviates, it will switch the MOSFET on/off to regulate heating.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: March 20, 2025, 09:02:45 pm
content: Quote from: john23 on March 13, 2025, 10:09:42 amIf you googlemodelling thermal inertia in spiceYou get some useful AI speil, showing how you can use long time constants in spice to model thermal inertia effects, and thus get a feel for how to tune your Analog control loop.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: March 20, 2025, 11:23:43 pm
content: nuts to AI, the solution is right here on our forumshttps://www.eevblog.com/forum/projects/how-to-simulate-thermal-processes-in-ltspice/(spoiler, yes it's just an RC network)

author: john23
author_rank: Frequent Contributor
timestamp: March 21, 2025, 07:09:10 am
content: Hello, SO is there some very good circuit (PID) maybe that you could reccomend?Thanks.

author: john23
author_rank: Frequent Contributor
timestamp: March 21, 2025, 02:58:07 pm
content: Hello,could you please draw what you mean So I could simulate it?Thanks.You can proceed with an Op-Amp (LM358), an NTC thermistor, a MOSFET (IRF540) and a resistive heater (10W).The op-amp will compare the thermistor voltage to a reference voltage. If the temperature deviates, it will switch the MOSFET on/off to regulate heating.

author: eutectique
author_rank: Frequent Contributor
timestamp: March 21, 2025, 03:42:52 pm
content: Quote from: john23 on March 21, 2025, 02:58:07 pmBecause it messes up the order in which people normally read text.Why is top-posting such a bad thing?Top-posting.What is the most annoying thing in forums, on usenet and in e-mail?

author: Terry Bites
author_rank: Super Contributor
timestamp: March 29, 2025, 03:46:03 pm
content: By differential do you mean a "PID" controller?This wiki page is helpful.https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controllerIt is the way to go for precsion control. The control loop can be analog or digital. Much as I loath digital (so boring) have a read of this.Seehttps://apmonitor.com/pdc/index.php/Main/ArduinoControl."Tuning" the PID coefficients to the external thermal circuit can be tricky.A heater and a thermal load will have a strong lag component.Tune the proportional P, add integral I, add the differential component D.Repeat, cry, try again. Or use a tuning algorithmhttps://docs.arduino.cc/libraries/pid-autotune/Check out this ingenious heater idea.https://www.edn.com/fixing-a-fundamental-flaw-of-self-sensing-transistor-thermostats/