Wes wrote:

Bruce L. Bergman wrote:


As for pre-installing the Back EMF Snubber on stock products, they
never know what type or voltage relay you're going to use with that
relay socket. But it would be a cool and useful factory option if you
are ordering production quantities of relay sockets.


Good point on the 1N4XXX. Should not have trusted memory. As far as the prewired diode,
I wanted it in the relay itself. AB makes some dc coil control relays with an internal
snubbing diode.

Wes
The diode is reverse biassed when power is applied. It conducts ald
allows the coil current to recirculate decaying slowly when power is
removed. It *never* sees the full back EMF spike as it shunts it before
it builds up. You'll never see a problem from the back EMF if the diode
is rated at twice the supply voltage so an 1N4001 is fine for a 24V
relay. The only 'gotyas' are that the diode *must* be rated to carry
the coil current and as the flux will decay a lot more slowly, the relay
*will* be slightly slower opening.