[sdiy] circuit protection question

[David]

Ahem... In my defense, good Sgt Murphy (or whatever his rank was) clearly
taught if there are two ways to do something and one will end in disaster,
someone will do it that way.

John should not have put holes or pads in his PCB which allowed me to bypass
his very well thought out protection with a jumper. In fact, all modules
should be totally encapsulated in the toughest epoxy possible to prevent
just such an occurrence! :) (this should be a very big tongue in cheek
grin...)

David

-- -----Original Message-----
-- From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-
-- bounces at dropmix.xs4all.nl] On Behalf Of Neil Johnson
-- Sent: Tuesday, December 14, 2010 4:59 PM
-- To: Tim Parkhurst
-- Cc: synth-diy DIY
-- Subject: Re: [sdiy] circuit protection question
-- 
-- Hi,
-- 
-- Tim Parkhurst wrote:
-- > The real solution (or at least part of a real solution) would be to
-- > use a keyed, polarized connector that cannot be plugged in backwards
-- > or out of position.
-- 
-- MOTM: good
-- Doepfer: bad (really bad...face-slappingly bad)
-- 
-- There is over-voltage to consider as well.  With the polyfuse approach
-- it is also quite straightforward to add a crowbar on each rail as well
-- (resistor, zener, SCR).
-- 
-- But any protection mechanism either needs to be good (adding cost) or
-- don't bother.  A half-baked protection mechanism is often worse as it
-- gives a false sense of security.
-- 
-- If you're going to fit polyfuses it might also be a good idea to fit
-- LEDs as well, so that you can quickly see if the polyfuse has tripped,
-- or something else is wrong.  Otherwise you could have users doing
-- "David's" with wire jumpers and then all that protection is for
-- naught.
-- 
-- Neil
-- (anyone else sitting in the United lounge at Washington Dulles this
evening?)
-- --
-- http://www.njohnson.co.uk
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