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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: programmable circuit breaker
Date: Wed, 5 Mar 2025 16:22:21 +0000
Organization: Poppy Records
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john larkin <jl@650pot.com> wrote:

[...]
> Maybe I shouldn't diode clamp the relay coils. I'll have to test the
> dropout time.

Put a resistor in series with the clamp diode, the value can be chosen
to keep the inductive spike just below the maximum allowable voltage and
that will give the fastest turn-off.  By using higher voltage switching
transistors you can have a higher voltage spike and a faster turn-off -
but there is the risk that the spike might be capacitively coupled to
somewhere vulnerable to damage.


-- 
~ Liz Tuddenham ~
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www.poppyrecords.co.uk