Try a PWMPot

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[Stephen Woodward] is familiar with digital potentiometers but is also familiar with their limitations. That spurred him to create the PWMPot which performs a similar function, but with better features than a traditional digital pot. Of course, he admits that this design has some limitations of its own, so — as usual — you have to make your design choices according to what’s important to you.

Perhaps the biggest limitation is that the PWMPot isn’t useful at even moderately high frequencies. The circuit works by driving two CMOS switches into an RC circuit. The switches’ inverted phase tends to cancel out any ripple in the signal.

The RC circuit is selected to trade response time with the precision of the final voltage output. The CMOS switches used are part of a 74HC4053B IC. While it might not solve all your digital potentiometer problems, there are cases where it will be just what you need.

We’ve looked at traditional digital pots before. If you prefer the hard way, grab a regular pot and a motor.



from Blog – Hackaday https://ift.tt/1PFmfEH

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