"IanM" wrote in message
...
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.

That's what I've wondered about electronic ignition. Do they use real high
voltage ignition coil switching transistors or would the magnetic field
still collapse fast enough to spark a spark plug with a diode? Or perhaps
they use a condenser (or equivalent) on the solid state components like they
do on ignition points.

RogerN