[sdiy] circuit protection question

[Harry Bissell]

That is a good method, but watch out fro the polyswitches. They can take a lot
of current to heat up and go into limiting. You might get a very hot diode before
they start limiting.

A nice side effect of polyswitch fuses is they have a small cold resistance (maybe
half and ohm or so) and limit inrush current to large filter caps, if you have them.

I don't do any reverse voltage protection in my circuits. I just don't wire them
backwards...

...or I kick myself in the @ss   :^)


H^) harry


----- Original Message -----
From: David G. Dixon <dixon at interchange.ubc.ca>
To: 'synth-diy DIY' <synth-diy at dropmix.xs4all.nl>
Sent: Tue, 14 Dec 2010 01:40:47 -0500 (EST)
Subject: [sdiy] circuit protection question

Here's a question for the gurus:

Do you generally bother with circuit protection, specifically against power
rail reversal?

If so, which technique do you typically use?

I'm thinking: power rail, to polyfuse, to reverse rectifier diode (e.g.,
1N4001) to ground, to circuit.  The diode will protect the circuit while the
polyfuse trips.  Does this seem like overkill?

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-- 
Harry Bissell & Nora Abdullah 4eva