In article , John Stumbles
wrote:
On Wed, 06 Jan 2010 16:54:59 +0000, Ian Bell wrote:

Pretty much but I was trying to avoid having a bleed resistor
permanently across the supply. The PSU has a lot of stored charge and
a bleed resistor that takes only a nominal 1% of the load current
would take about 5 minutes to discharge it. That in itself is not a
problem as the PSU is in an enclosure but when I am testing it, it is
a pain to have to wait that long.

That's a different problem. I think what I was proposing
addresses the original problem, but if you want to make it safe for
yourself to prod around in the PSU arbitrarily I suspect that's going to
be a non-trivial problem to solve.

The simplest solution is to have an additional, low value, bleed resistor
soldered across the caps during the period of development. Then clip them
off when finished, check the behaviour is still OK, and stop.

But as you say, your situation as someone developing and testing a circuit
is quite different to that of the end user. So the primary requirement is
to take due care and use whatever extra safety methods seem relevant during
development.

Slainte,

Jim

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