Re: DC relay latching voltage

On 2024-08-23 12:43 p.m., Don Y wrote:

On 8/23/2024 7:36 AM, John Robertson wrote:

I assume you have the normal back diode across the coil for clamping
the ringing voltage.

If you care about the life of the relay (and how well it "opens"),
a better approach is to add a zener rated at the coil voltage in
series with that diode.  The diode, by itself, delays opening of
the contacts and leads to more opportunities for arcing.  The
zener speeds up this transition.

Hi Don,

Don't you mean that one could use a zener diode in place of the back-EMF
diode - or parallel with it?

We've been using 1N400X (and 3A in some cases)diodes since the 70s for
protecting pinball driver transistors - not too worried about the decay
time so haven't really looked deeper into it before.

Thanks,

John :-#)#

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