Changing potentiometer values?

[Ell]

I want to make a Valvecaster tonight but I only have 500k (A and B) pots, and a 20k B pot. Is there a way for me to turn any of these pots into a 100k pot using resistors?

[.Mike]

Take a look here: http://www.diystompboxes.com/analogalchemy/emh/emh.html

[ringworm]

Can I ask a question about the EMH. It says I have to put a resistor on each of the outer legs (1 & 3) and attach them to the central leg (2), is this right? I was under the impression that pot adjustments were done from legs 2 to 3? I'm sure this topic is talked to death here but I keep finding conflicting info and I only ask because I need to make a 1M rev log pot and it tells me I need to put a 4M7 between 1 & 2 and a 110k between 2 & 3 (or roughly those values).

[MohiZ]

The EMH is correct. You have to note that there's no way to fake a real pot with resistors so that it'll work exactly the same. The calculator gives a solution that's acceptable for most uses, but it depends on the circuit. For instance, if the schematic only uses two of the pot's legs (so that the wiper is tied together with either of the outer legs), you can just add a single resistor after or before the pot.

[ringworm]

Ok, thanks for that. I'll remember to check against the schematic.