EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Arcadium on March 21, 2022, 06:45:13 pm
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Hello,
I am making a project where I try to control heating element with type K thermocouple and AC heater. I have previously did one with DC heater, but now I need some professional help.
My circuit for DC heater worked, but I have little experience in circuit design and this one will have 50 or so heater/thermocouple segments. (heater and thermocouple I have: https://www.aliexpress.com/item/32869555292.html?spm=a2g0o.order_list.0.0.21ef1802IzJAHI (https://www.aliexpress.com/item/32869555292.html?spm=a2g0o.order_list.0.0.21ef1802IzJAHI) ).
It should be not too expensive and reliable. I will use Arduino microcontroller and would like to use PWM pins to control it, for the reading MAX6675 chip can be used.
If it's possible to make a closed loop system without using microcontroller it would be perfect, but I don't think it can be done cheap for such quantity.
If someone could come up with the schematic and components that would be great, I'm willing to pay a bit if I can get schematics and BOM.
I know that forum is more for helping to learn and come up with solution and not for providing one, but in this project I'm trying to program Arduino chip directly and there is a lot to learn there(first time with bit operations). I don't want to introduce a lot of variables because I'll go crazy trying to find what's wrong.
Anyways, even the general advice is welcome, worst case scenario I'll try to make it myself.
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One can build a temperature regulator the old analog way. If only crude proportional control is needed howver analog control could be very viable. So it depends an the required accuracy and speed. However this gets a bit cumbersome with a PI or PID regulator and the often relatively long time constants (e.g. > 1 second) for the thermal system and tuning may need soldering. So it makes sense to use a µC. Another reason to use a µC would be if more than just a constant temperature is needed, like some ramps or additional functions.
For a cost effective system, especially with multiple channels, one could get away without the relatively expensive MAX6675.
One may consider an external ADC, or maybe just external amplification.
The required speed of the system would determin how many channels a single µC could serve.
There are some relatively cheap temperature controlers from China, that may do the job.