"Larry W4CSC" wrote in message
...
"Roger Long" wrote in
:

Did I blow the diode by hooking up with reverse
polarity?


Yep. The diode only conducts when the field in the coil of the relay
collapses, when you turn the power to it off. The diode is reverse biased
(+ power to its banded cathode end, - power to its anode) when the relay
is
energized. You had it connected up backward, zapping the diode to a
short.

Oops....

+12-------coil----------12

| |
--|--
band noband

Not clear. Fuse is blown but one would have to check to see if the diode is
blown. Suppression diodes are generally rugged little things. They may well
last long enough to blow the fuse without going out.

There are only a zillion or two diodes launched in this application. I
don't think I would use a solenoid or a relay without one. If worried get a
bigger diode.