D Wysong wrote:
> Still wondering what the underlying circuit looks like,
> though. With the batt/alt switch ON and the engine not
> turning the lamp should light. With "C" sitting at the
batt
> bus voltage in this case, "L" must be pulled low to
> complete the circuit (light the lamp).
Yes. The "L" terminal is either open (call it infinite
resistance; system nominally working) or at ground -- lamp
lit, not working. There's a transistor switch in there to
accomplish that, and voltage must be supplied from the
outside. So, voltage measurements at the "L" terminal with
accompanying circuitry will be consistent with only "on or
off."
The volts at which the lamp is on or off is a grain-of-salt
matter. It has to be set low enough (through a dirt-simple
reference diode inside the regulator) so that "off" does not
necessarily mean the battery is being sufficiently charged.
A/k/a as a "tit on a boar hog." :-)
Reg,
Fred F.
|