[sdiy] Need help breadboarding a VCF

[Harry Bissell Jr]

Don't have the schematic in front of me.

If this is an OTA based filter... the expo converter
should source current to the negative rail. If you put
an resistor from the expo output to the negative rail,
you should see a voltage change across the resistor
when you change the control voltage.

741 opamps will not perform 'well' but it sould still
function imho.  OK for a first try.

Solderless breadboards svck harder than BBDs imho. Too
often a single flakey conection wastes hours of time
when it would otherwise be perfect. Other people like
these things, so there is no accounting for taste.

H^) harry

--- Jeff Farr <moogah at gmail.com> wrote:

> 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?
> 
>