[sdiy] VCO bleed through to other modules

[Rykhaard D.A.M.I.A.N.]

In about '92, my then online eletronics mentor, gave me a couple of
tips about my power supply distribution to each module, which I've
used ever since - and I've never had crosstalk troubles. :)

First

(Sideline thought before 'First' - and I'm going to graphically make
this example and post it on my webpage, right after this message is
finished - to hopefully help others)

>From my power supply (Power One bipolar 12V @ 1.7 amps, tuned to
bipolar 15.0 @ 1.5 amps) is sent directly to a:

- positive supply bussbar
- ground bussbar
- negative supply bussbar

- Every PCB, gets it's power feed from these bussbars, through a 4
conductor 22 guage shielded cable.

- The 4 cond. cable ending at the PCB is feeding;

-- a 100uF electrolytic cap. for the +V, through a 22ohm 1/4 watt
resistor.  (3 of which have saved me in the past few months, on 3
shorts.  Thank you resistors!! :D )
-- a 100uF electrolytic cap. for the -V, through a 22ohm 1/4 watt resistor.
-- the ground plane, of the entire PCB

UNTIL this building start (July 2005), I'd rarely been using 0.1uF
ceramic caps as buffers on chips of my PCBs.  I'd read a LOT before I
started any building last year, and have 1 x 0.1uF cerm. cap., on
EVERY single chip, as close to it's power pins as possible.

On THIS building session, I start twisting multiple wires to the pots
and / or jacks from the PCB, together, to hopefully help cancel out
any potential leakages of signals.  (I had NOT done this in my
previous building, from '91 to '98.)

>From '91 to about '94, I used 1/4" jacks in my 1/8" aluminaminiumnium
( ;) ) panels, withOUT an extra ground wire to any of them.
In about '94, I switched to (then known as EF Johnson) banana jacks,
which I've used ever since.  (With a banana to 1/4" conversion pair
for my outputs.)

I've NEVER, had any crosstalk. :)  I've been told a couple of times,
that my 100uF caps. are overkill - but as soon as I started using
them, the previous problems that I was having with more than 2 or 3
modules, completely disappeared. :)

(From all of the reading, and recent digital work - I FINALLY learned
how well buffer caps per chip, WORKS. :O  In my previous 'Deathlehem
Machine' builds, every single one of the 6 of THEM had ...... (what
would I call it?) cross-CLOCK problems. :O  (Whether they were CD4011;
LF347 or 2N3904 based clocks / oscillators.)

K.  Off to make a graphic example of this, for my webpage, which will
be posted tonight. :)
I hope this helps.  I can't at the moment, think of any other
solutions, that haven't been already mentioned. :O :)

--
Take care,
Warmth and Peace,
Ryk

My NEW webpage home:
http://www.sdiy.org/damian/index.html - still transferring all from
the old site - Mar 1906

http://deathlehem.bravehost.com/damian.html - my modular synthesizer,
D.A.M.I.A.N.;s webpage