Help with PID Temperature Control

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Help with PID Temperature Control on: April 30, 2021, 01:50:05 AM
Hi there!

I've been attempting to replicate the PID control tutorial found here: http://electronoobs.com/eng_arduino_tut24.php

I've made a few small changes - no LCD, no encoder, and I've replaced the 12V heater with a piece of nichrome wire. The rest of the connections are the same.

I think I may be making some sort of rudimentary error when it comes to connecting my power supply. When I connect the positive terminal of my power supply to the wire and the negative terminal to my resistor, the thermocouple reading jumps to >400ºC but the wire does not heat up. When I swap the terminals so that negative is connected to the wire and positive to the resistor the thermocouple reading goes to 0ºC but still the wire does not heat.

If anyone has any insight into what I may be doing wrong, I would greatly appreciate the help!

I'm happy to provide pictures of my breadboard set up if that would be helpful.



Re: Help with PID Temperature Control Reply #1 on: April 30, 2021, 09:13:22 AM
DO you have direct connection with the thermocouple? Maybe there is a short circuit with the thermocouple wires inside?



Re: Help with PID Temperature Control Reply #2 on: April 30, 2021, 01:26:15 PM
I had the wire tip of the thermocouple just wrapped around my nichrome wire. Even if I do remove the thermocouple from the wire and adjusts the PWM value output to pin D3 manually (tried 0, 255, 127) the wire does not heat regardless of where I connect the positive/negative power terminals.



Re: Help with PID Temperature Control Reply #3 on: May 04, 2021, 08:47:00 AM
Maybe you've burned out the MOSFET? If the nichrome is very short, its resistance would be so low that it would be basically a short-circuit and that would create a huge current spike that could burn your components... What is the resistance of your nichrome wire and at what voltage you supply it?