[sdiy] power supply

[Tim Parkhurst]

Here's one thing I always check on a new circuit (and I'm surprised no one
has brought this up yet): BEFORE you apply power to the circuit, use a good
meter to check the resistance across the power supply lines going into the
circuit. You will probably read a low resistance (somewhere around ten to
100 Ohms), but this is okay. You basically are just checking to make sure
you don't have a dead short from + or - to ground. The resistance may also
change slightly as decoupling and/or filter caps charge up (the meter
applies a voltage to the circuit), but again, you are checking just to make
sure you don't have a dead short.

Comments?

Tim (dead shorts) Servo

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-----Original Message-----
From: harrybissell [mailto:harrybissell at prodigy.net] 
Sent: Thursday, July 29, 2004 5:22 PM
To: charles kerr
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] power supply

Hi Charles....

DON'T use a battery for an initial test. Batteries are capable of
MASSIVE current into
a short circuit... enough to start a fire in most cases.

I prefer a commercial power supply like a PowerOne (or similar) linear
supply... maybe good
for 400 - 800mA with current limit built in.  Then when I apply power, I
watch the supply voltage.
If it holds +/-15V (what I use)...  then I leave it on and watch for
excess heat.  If the voltage is
wrong I shut down right away.

I have yet to fry a commercial supply....

H^) harry

charles kerr wrote:

> hello everyone,a question and topic change, how do all you synth
> diyers power your trial circuits? is it best to try out on breadboard
> with a battery power supply? I was thinking of (I have a Doepfer case
> with +12v, -12v, 0v and +5v) putting the power out to a blank
> faceplate and then jacking out of sockets to crocodile clips onto a
> breadboard/proto circuit but I got to thinking that if I make any
> mistakes in the circuit than I could mash up my whole synth power
> supply, would it be alright if I inserted a fuse? but what rating etc?
> With batteries the supply would not be very constant would it, the
> supply would drop gradually and over the time that I am trying things
> out I would be spending an awful lot on batteries, something I would
> like to avoid if possible.I have noticed that a lot of synth diy stuff
> is on a 15v power supply so I was considering buying a Blacet supply
> and using this as a main source for a modular - but for the same
> reason as above I would prefer to keep this for finished modules. i
> think what I need is a small 15v supply with enough ampage for one
> module, where can I get one from? all bench supplies I see are +15v
> but don't have -15v (same with 12v) could anyone reccomend a solution?
> no doubt anyone who has read this far is thinking "duur - what a
> twit!" but if you could help me out I would be eternally grateful
> thanks for reading and thanks in advance for any responsecharlie   If
> anyone has read this far
> -----------------------------------------------------------------------
> ALL-NEW Yahoo! Messenger - all new features - even more fun!



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