Phase angle sketch for arduino

Thread Starter

white aurora

Joined Sep 26, 2019
Hi All,
I have an SCR lower control board for a treadmill. I would like to eliminate the upper board. I have reverse engineered the lower board(this is the first circuit I have ever done this with so may have some inaccuracies). Also, sorry for the upside down pinout. It has a 10 pin cable going between upper and lower boards.
Pin 8 has a square wave of around 8ms going out to the upper board(half AC wave at 60hz?). I have had difficulty getting a clear signal from pin 10 coming from the upper board while it is running. I know from the diagram that this signal is smoothed and sent to the phototriac gate(S21MD3V).
zero cross.jpg

So, my question is, since I have a zero cross signal, and I know it goes to the phototriac, how do I control this? Can I use arduino to create a phase angle control? could I use a potentiometer and a capacitor to manually adjust the delay after zero cross and control the speed that way?

I am relatively new to electronics and new to arduino. Everything that I have found on phase control includes building the entire circuit using microcontrollers or discrete components. As I understand it I only need to build a very basic part of the circuit but have been unable to find a specific answer to the challenge.

Thank you in advance to everyone with more advanced understanding than mine.

MOD: Corrected Pin Orientation.ESCR control board.jpg
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