Converting PWM controller potentiometer to digital (rockerswitch interface)

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Valtsu

Joined Oct 31, 2022
1
I have made my own heated jacket and the power control is done by PWM switch installed into my motorcycle. It has by default an analog potentiometer with switch but I would prefer to have a digital potentiometer that I could control through simple rocker switch as I have for my heated grips.
Goal would be to have only 4 to 5 steps.

I am not familiar with the science behind this particular PWM controller that seems to be much more complicated than basic 555 chip operated versions. This brings me to the problem that I have.

The analog potertiometer receives ~5V current from the circuit side and its resistance varies between 4 ohm and 12,5k ohm. I havent been able to find a digipot with that low internal resistance nor with 12,5k ohm upper limit. They "all" seem to stop at 10k ohm and start from +40ohm. I dont know if this is a problem in anyway due to the lack of understanding. One last thing is that most of the digital ones seem to have a high number of steps (31-1000) and in my use case its not desirable.

How would you recommed me to solve this issue? Just throw a 10kohm digipot or should it match the original?

I have been playing around with the idea of buying just the chip and solder it myself and sinking into an epoxy for protection or buying and ready board..

PWM contoller that i have is this one:
https://www.amazon.de/Controller-Ov...pd_rd_i=B075FTQ334&psc=1&ref_=pd_bap_d_rp_1_t
 

Sensacell

Joined Jun 19, 2012
3,098
Program a small MCU to output the PWM and monitor some switch inputs.

By the time you cobble a bunch of parts around a 555 to do what you want, it will become a complex beast.
 

Irving

Joined Jan 30, 2016
3,190
Yes, a simple microcontroller and rocker switch would do the job. The analog pot produces a voltage from 0 to 5v - the resistance isn't really relevant - which changes the duty cycle. A small MCU programmed with 4 or 5 output voltages from 0 - 5v and selected sequentially would replace the analog pot. One of the ATMEL 14pin AVR chips with a built-in digital-to-analog converter would be my choice rather than messing around with PWM. Let me know if you'd like more info.
 

Ian0

Joined Aug 7, 2020
6,706
Even simpler, you could use a push button switch to clock a 4017, which could switch different resistors into the 555 timing circuit.
 

Irving

Joined Jan 30, 2016
3,190
Even simpler, you could use a push button switch to clock a 4017, which could switch different resistors into the 555 timing circuit.
But the board requires a DC voltage, not a PWM signal, and there's no way to predict how the on-board chip will respond to poorly filtered PWM voltage synthesis. I'm not sure a 4017 etc. is any simpler than this:

1667226254956.png
 
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