Hi sn7ke
Using a multimeter and a potentiometer i've worked out that i need about 80-200ohms hooked into the power supply to give a reliable voltage crash on my SA-20.
This is how to turn any 0-whatever pot into an A-B pot (in this case 80-200ohm)
the mini-circuit consists of 2 pre set resisters and a pot as shown below
----------Resister A----Pot------------------
\ /
\-------Resister B---------/
Resister B should be your top ohmage so 200ohm.
Use the formula A = RB/B-R to get the value of the other resister. (this assumes that the pot goes down to 0ohm)
for me R=80, B=200 so
A = 16000/120 = 133 ohms
now we have an idea of the resister's values, check the top resistance. P is the pot value, 100k in this case.
Top R = B(A+P)/(A+B+P) = 200(110+100000)/(110+200+100000)=199ohms
so solder some resisters together and we have an 80ohm-200ohm pot!
I generally use preset pots for A & B so that i can tweak, but this is how you get the starting values.
BTW Use a logarithmic pot with this technique to get a linear scale, linear pots creates a inverse log scaling effect for those who are interested
good thinking. and good description of applying. thanks-