Ldr's as Pots

[yobleduwop]

Has anyone looked at using something different to pots? maybe ldrs or something smaller? would this have much of an advantage in analogue effects?
Thanks joel

[daverdave]

I've thought about using ldr's, but they can be a bit impractical considering that your settings would change every time light hit them, but for wah and filter effects they'd be alreet. Or you could make them switchable with pots for different parameters, that'd be sweet.

[Sir H C]

Maxim and some other IC companies make analog pots that are digitally controlled controlled:

http://www.maxim-ic.com/DigitalPotentiometers.cfm

The problem with LDRs is that you can only use them as a pot with the wiper tied to one side, unless you use two in series with the light sources out of phase.

[Eb7+9]

I recently came up with a (fairly) linear voltage controlled pot using two opto's and four transistors but I just don't know where I'm gonna use it ... at least it's continuous ...

[zachomega]

Then of course you have to power the lights...Powering the lights is pretty wastefull...

Additionally, incandescent bulbs tend to be slow in regard to how fast they can change how lit they are...

LED's on the other hand don't change too much from minimum to maximum brightness...

and both types of bulb suffer from thresholds before they actually light up. 

-Zach Omega

[Seljer]

^^the LDRs aren't too fast either

[The Tone God]

You can check out the "Rock N' Control" article which touches on the topic.

Digital pots have many restrictions as do LDRs. If you are replacing a part you have to figure out what it's function is and what properties are important to that function to find a suitable replacement.

Andrew

[MetalGuy]

Has anyone looked at using something different to pots? maybe ldrs or something smaller? would this have much of an advantage in analogue effects?

LDR pots are good for a programmable all tube preamp for example where regular digital pots because of their signal handling limitations can not be used. There's a special thread about this at the Music Electronics Forum:

http://music-electronics-forum.com//showthread.php?t=1015

For a fully capable standart tube preamp tone stack however you'll need a 4 terminal LDR which unfortunately is not available - you'll have to build it yourself. Obviously this is not so for Mesa.