caps and pot

[peterg]

How do I wire a pot and caps to get values ranging from 0.01uf to 0.068uf? What value should the pot be?

[ashcat_lt]

Don't work that way, I'm afraid.  Depending on what you want that "cap" to actually do, we might be able to figure something, but without some clue as to the final application, all I can say is it don't work that way.

[blackieNYC]

Audio passing thru these caps?  You might be able to split your signal to two caps and use a pot to pan between them. This is done on the input of some fuzzes. Exact values may be elusive.
If this is for an RC filter, you know that you can get what you want with a fixed cap and a variable resistor.

[armdnrdy]

Easily accomplished with a rotary switch.

[bluebunny]

As the guys say, you need to say what you're trying to achieve.  Pots don't change the capacitance of a capacitor. 

[MrStab]

if you go down the pot-into-parallel-cap route, hook up the pot and cap and use a capacitance meter (or one of those handy transistor testors you can find on eBay etc.) to find the usable range. adjust pot size and place a fixed resistor as necessary. prepare for ESR affecting any impedance or gain - though it was relatively small when i tried it.

[peterg]

Thanks Guys

I am planning to mod a Crybaby to be able to adjust the lower range.  See links below.

http://stinkfoot.se/archives/549
http://www.electrosmash.com/crybaby-gcb-95

The standard cap is 0.01uf and the bass crybaby cap is 0.068uf.

I found a mod which entails adding a stitch to switch between the 2 caps but I'm hoping to add a pot to get more range control.

Is this possible?

I'm also doing the true bypass mod so the input buffer will be removed.

[armdnrdy]

Google Dunlop 535Q schematic.

Take a look at how Dunlop uses a rotary switch to switch between six caps.

This is a very versatile configuration.

If you must use a pot...check out a Big Muff tone control.

You might be able to find something usable by messing with the values in the Duncan tone stack calculator.

http://www.duncanamps.com/tsc/

[ashcat_lt]

Funny.  When I was posting above I was thinking about how according to RG a crybaby is an example of one way to achieve a variable capacitance. 

For what you're trying to do, I think "panning" between the caps like blackieNYC mentioned above is kinda your best bet.