[sdiy] Starting a synth project

[John Loffink]

I second (or third?) the recommendation to buy an off the shelf power supply
and start by building some simple fun stuff: LFOs, S&Hs, etc.  Chances are
you may have an analog synthesizer that you can interface these to already.

Condor and Power One are good brands.  Make sure it is a linear supply, not
switching.  You probably want +/- 15 volts and may want to consider 5 volts
as well if you'll add much logic circuitry.

Some of the proceeding comments reminded me of a friend I helped out in the
mid 1980s on some DIY circuits he had built.  He built a power supply, LFO,
S&H, and some other simple circuitry, but none of it worked "except" the
power supply.  After some troubleshooting I discovered an error in the power
supply.  When measured under no load it looked okay, but once the DIY
circuits were applied it pulled down one of the rails to zero.  He was
looking at the wrong part of the circuit to fix the problem.  Basic rule of
thumb, always check the power first!

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com


> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl [mailto:owner-synth-
> diy at dropmix.xs4all.nl] On Behalf Of Gene Stopp
> Sent: Monday, December 27, 2004 1:25 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Starting a synth project
> 
> Harry speaks much wisdom. I remember learning synth modules by
> concentrating
> on the modules themselves and taking the power supply for granted. After a
> while you get a feel for things like when a 1/2 watt resistor should be
> used
> instead of 1/4 watt, or when and where to place bypass caps, things like
> that. Power supply design goes much better once you have "the feel".
> 
> And a quick glance at eBay shows, let's see... aha! TWO Power One +/-15 @
> 5
> amp supplies for $19.99 for both with no reserve and zero bids, one day to
> go on a seven day auction. Not bad! Those are going to be big and heavy,
> but
> at five amps per rail you could power about a hundred modules. And have a
> spare.
> 
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58288&item=38621291
> 58
> &rd=1
>