exponential VCO problems

[Eric Barbour]

Forgive me for poking in here with a trenchant
comment or two......

  All this talk about linear-to-exponential curcuits just reminds me
(once again) why I went to vacuum tubes. These drift and linearity
problems don't happen with tubes. (They just have another set of
problems....but at least they DON'T DRIFT WITH TEMPERATURE!!)

  And the power-supply woes....I feel your pain, really do. Many times
this happened to me, also. And I often got PAID to fix these problems.
Here's a novel idea: why not have RC supply isolation networks
(decoupling networks) throughout the circuit? One pair per op-amp
or other chip? 

  This method is near-universal in the tube world, and it
makes debugging VERY easy. The resistors act as fuses, or at least a
short will make itself apparent by an overheated resistor.

  That, and sockets on everything (soldering a tube into a circuit is
very rare). I recall that Paia 2700 and 4700 modules also had decoupling
for each PC board.

Keep the above in mind when building your next gadget......

-- 
Eric Barbour
Svetlana Electron Devices
Portola Valley CA USA