[sdiy] buffering outputs and routing signals (SEM modular related)

[Magnus Danielson]

From: klosmon <klosmon at earthlink.net>
Subject: Re: [sdiy] buffering outputs and routing signals (SEM modular related)
Date: Sun, 25 Jul 2004 10:48:10 -0500
Message-ID: <3.0.1.32.20040725104810.00afe410 at earthlink.net>

> At 06:53 PM 7/25/2004 +0200, Magnificent Magnus wrote:
> >Hi Nico!
> >So, there is no buffers, but then most signals will be from within the
> box, so
> >it is only patching around on the same supply.
> >
> 
> Good point -- and a distinction that needs to be made in this case.  If
> you're only going to be patching the synth & not using the patch-points to
> interface with the outside world, no buffers are required.

Right. Whatever voltage you are going to see it is design to handle anyway.

> HOWEVER, if you (or the synth's next owner) someday decide to see how that
> auxillary piece of circuitry will fit into the system, there's always the
> potential for damaging the Oberheim circuitry (just serviced a unit a few
> months ago, for a user who'd patched out EVERY SINGLE MOLEX point on the
> two voice boards, the keyboard board, and the mini-sequencer.   He'd
> managed to kill some ICs on every board -- not sure what he'd plugged in;
> but I know he'd never even heard of buffering).

Well, of course there is a good chance of killing something when doing careless
patching, but I just felt it was alot of hassle to do so many buffers. I have
pulled out almost all patch-points, only left a few unused (Trig for envelopes
not pulled out as well as secondary CV inputs for oscillators and filter, which
saves me 5 signals which was necessary due to lack of board-space).

One always have to use some common sense when patching things in. Also, using
buffers may not really save your day fully. A real over-protection design is
really what you want anyway. Diodes to the power-supply lines and a series-
resistor for current-limiting could do minor successs as an over-protection
circuit.

I have too repaired toasted SEMs. It was only after that I got a bad need for
a couple, which I eventually got.

BTW. Damn Intersil not to keep CA3080 in production!

Cheers,
Magnus