[sdiy] which zener and current limiting resistor?

[Benjamin Riggs]

Another solution is use a resistor between the +V side of each pot and the
=15V rail ie. if you have a 10k pot and want it to sweep 0V-10V then put a
5k resistor between the +V pin on the pot and the +15V rail.

Ben.

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of keith sterling
Sent: Friday, 11 August 2006 3:31 AM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] which zener and current limiting resistor?

I have a synth with a +-15V supply and need 16 pots to wipe from 10V to 
GND and 2 pots to wipe from 5V to GND for cv generation.  So I think I 
need 2 zener diodes to generate the 10V and the 5V.  How do I calculate 
the size of the current limiting resistor and current rating of the 
diodes?  My supply doesn't have a lot of headroom so less current drawn 
is better.

I tried using a 2 resistor voltage divider but then every control 
affected all the other controls!  Pretty hard to dial in a sound that 
way!

cheers,
keith sterling