Need advise on PIC controlling a variable resistor

[Acetronics2]

Hi, Baldwicks

if your tone steps are not too short in time ... you could use an ALPS motorized pot ( see i.e. www.selectronic.fr ref 50.6278 as an example ) and a PIC to control the output freq and then correct the pot as desired. A kind of servo motor ... driven to give freq instead of position.

you could then also keep manual drive of the freq ...

Alain

[sougata]

Hi,

If you are using a VCO then you might use a few more pins on the PIC to shift the voltage level on both ends of the POT. Your options are high = 5 volts, low = 0 volts and input = HighZ.

In this way you would increase the resolution of the whole thing.So your software would control the voltage ranges between say,

0v to 1v
1v to 2v
3v to 4v
4v to 5v

and you get 256 steps on each. Since it is a self oscillator you can feed the osillator signal back to the PIC and make a dynamic calibration routine for drifts in your ladder DA circuit + POT.


Wishing a speedy recovery to our forum member steve who is hurt in a car accident.

Best Regards
Sougata