On 9 Jun 2004 19:43:32 -0400, (DoN. Nichols) wrote:
I seem to remember something else for that purpose. Like a
zener, it does not turn on until it reaches a threshold voltage, but
unlike a zener, it does not remain at that voltage drop -- instead it
switches to an extremely low voltage drop. (Consider it to be like a
Zener diode connected between the gate an anode of an SCR, so when
things reach the right voltage, the SCR is turned on, and all the
current is dumped into the coil.

That would be a Diac.

Gary