Potentiometer conversion help.

[diblit]

im building this tubescreamer clone and i want a toggle switch between 2 pots. for example, 100k and 1M, but i dont want to have 2 pots on the pedal for drive, i just want one..  im not totally sure which ones i want to switch between yet though.
what size resistor would i solder across lugs 1 and 3 to make a 1M into a 100k, 250K or a 500K. do i need multiple resistors or will just one do it?

thanks for your time fellow diy'ers!!!!!!

[shawnee]

You really need to use the same value resistor across lugs 1-3 as the pot so that the taper stays the same if you go with parallel resistance.  You could use a 1M resistor and a 1M pot and that would give you 500K with the switch on. Another option may be to simply add a resistor in series with the pot and then you could use any value that you want.

[mgwhit]

You can only lower the value by adding parallel resistors across the pot, so you'll have to start with the largest value pot you'd like and work down.  Here's the best resource I know of on the subject including diagrams and formulas: The Secret Life of Pots, by R.G. Keen.  Good luck!

[Haberdasher]

http://www.sengpielaudio.com/calculator-paralresist.htm

a useful tool

[diblit]

Thanks guys. you are all awesome!! very much appreciated and very helpfull.