Back in the days when all cars had a headlight relay, did you EVER see anybody who got stuck in the dark by that failure? I didn't. The US car makers made pretty good choices on that particular set of issues.
Now, I don't mean Lucas.
Headlamp bulbs - -96 LHS
Jan 18, 2007
43 Replies
Good point.
It's understood that you have at least one relay for highs, one for lows. You couldn't have indpendent control of hi/lo beam with one relay. When I say one or two relays, I mean one or two for each (hi beam or for low beam).
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
Well I am not Daniel Stern but I will take a shot at it anyway. A system as you describe it would require a blocking diode to be installed between the relay contact connected to the lamp wiring and the existing wiring from the switch/ relay coil otherwise as soon as the relay pulled in it would override the switch and self energize causing it to never turn off.
Hah! Right you are. It's called a latching relay circuit. And to think - just last week I designed a circuit that was *intentionally* designed to do just that (latch after initialization). :)
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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