Bypassing POT on PWM motor controller

Other Hardware Motors, Mechanics, Power and CNC
1

I am trying to bypass POT on PWM controller but wanted to get input before going down this route - just to make sure I am not missing anything.

The controller has two SA555 which I am guessing is to drive two separate banks of mosfets (two banks of 4). I was able to apply arduino PWM output to each of them on PIN 3 and control a smaller 24v motor.

Pin 1 has 12volt input - even though I was able to use 5v PWM from Arduino.

Below is the plan and please let me know if I am missing something and should avoid this route:

  1. Will run PWM with opto-isolator to go PWM from 5v to 12v that will be applied to pin 3.

  2. Since there are two SA555 chips, I could run two separate PWMs to each and sync them (or should I just use one and hook to both pins?).

3.Optocoupler supports up to 20khz. Should I just keep Arduino default 490 or 980hz?

Is there a consideration I am missing? Here is a physical overview of the controller.

P.S. I am also able to connect with DAC MCP4725 to the POT input but wanted to simplify the design by taking out DAC and ADC parts.

SA555
SA555188×125 4.82 KB

IMG_0075
IMG_00751512×2016 294 KB

2

Missing a data sheet that eliminates the contradictory or missing information about the controller.

3

Yes, unfortunately, I couldn't find any more information about the controller except of the youtube video that describes the hardware. I was hoping to get a feedback based on generally how these type of controllers are designed.

Or, in general, if there were any red flags based on limited information I have.