Converting Pots to Digital?

[joner]

Hello,

I'm new to this site, but am hoping its the answer to the thousands of questions I have as a newbie.

What I'm trying to find out is how to replace some of the pots in my effects boxes with digital potentiometers. My goal would be to have greater control over the settings so I can fine tune things like the rate on my delay pedal. Any thoughts? Schematics? Things to be aware of?

Any help would be great!

Jonas

[niftydog]

well, you're certainly not the first to ask a similar question. As R.G. has said in the past, paraphrasing here; "if it was easy, everyone would be doing it".

Unfortunately there are some drawbacks when using digital pots, not the least of which is the amount of current they can handle.

For new designs, this can be gotten around. But, as far as dropping them in existing circuits... well that can be tricky.

follow this link and you'll find some application notes that may help explain their use in more detail. Take particular note of the article titled "Audio Gain Control Using Digital Potentiometers"

Also, similar thing from a different manufacturer.

There's some limited discussion at this forum, try searching for "digital and potentiometer" but you won't find much that will make you happy!

Sorry!

I'm looking into the design issues for a project of my own. I'll certainly let the forum know if I have a Eureka moment.

[mikeb]

If all you're looking to do is have finer control over a certain parameter, you can use a setup consisting of the original pot (say 100k) and then add another pot in series of 1/10th the value (say 10k). Assuming only two pins of the original pot are used (i.e. it is used as a variable resistor), then the second pot will give you a 'fine tune' control. If all three pins of the pot are used it is still possible to do something similar, but will depend on the circuit as to the 'best approach'.

If it is the 'digital' control you are after, by the time you research the circuit you have, research the digital pots, locate them and buy them (they're expensive) you would probably be better off redesigning and building the thing from scratch with voltage control uppermost in your mind - IMHO.

Perhaps one question for all people to consider is - how much is my time worth? Once that is decided, the best way of approaching DIY can be more easily selected!

Mike

[petemoore]

Probably different than what you're asking about...
 Analog Alchemy has a Mosfet Controller....