[sdiy] Need help breadboarding a VCF

[Jeff Farr]

Hello, I'm working with the "Filter Option 1" schematic in the EN
Preferred Circuits Collection, and so far, it doesn't work..  Firstly
I should ask if there is a less complicated filter I should start
with, this one barely fits on my radio shack breadboard and the mess
of jumpers makes it a bit difficult to troubleshoot.  What I would
like is some type of scheme for testing the expo converter, as so far
it doesn't seem to be working as I would expect.  I've hooked it up
alone on the board and tried to measure the current it produces, but
it remains constant where I would expect it to change.
Three questions:
I'm using the common terminal on my PSU as ground, is this correct?
I don't have any 307's so I'm using lm741's instead, perhaps this is
the problem?