Michael,
You asked for a brief description of what a relay does: [probably
wont be that brief by the time i get it done (:- ]
It is a small electronic devise that takes the load (amperage) off
the wiring and switch componentry in a circuit. This allows
considerable cost savings as the wiring to take the load of the
devise that the relay is driving only needs to have higher load
rating wire from the power source (fuse box usually) to the relay
and then to the devise (e.g. headlights or heater/aircond unit
etc.). The switch is only required to take the load that is the
equivalent of a 12v impulse (very low ampere draw) to excite the
relay coil and close the contacts to complete the high amperage
circuit and supply power (voltage + amperes) to the devise. This
technology has allowed manufacturers of switch gear to concentrate
on the quality of the switching mechanism - remember the P76 of
the 70's that had neither of high quality which was one of the
major downfalls of the car).
Typically in the modern day car you'll find a black box somewhere
near the battery that's full of circuit breakers and relays and
not scattered so much around the car as was the case in the early
80's. In the '70's ala 510, you'll only find a relay or 2 in the
whole car - lights, horn, and sometimes a start relay, auto trans
models have a combined backup light & inhibitor relay and that's
about it, so our 510's must have a tonne of wire in them and
fairly high quality switches that's just not needed. Nissan were a
bit smarter than most manufacturers in once sense and a right pain
in ar$e in the other as they "hot" wired most of the components.
What this does is make the switches just earth the circuit to
complete it and the load goes through the devise first. The downer
is that the circuit protection and the earthing circuitry has to
be absolutely in perfect working order to avoid electrical
gremlins that are just so difficult to track down.
regards,
--
Terry (i hope this explains it a bit for you)
"You win some, you lose some, you wreck some."
Dale Earnhardt
> To: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
> From: "Foreshew, Michael, HiServ/AU"
<[EMAIL PROTECTED]>
> Subject: RE: 1600 Headlight Improvements & other stuff !!!!
> Date: Thu, 23 Mar 2000 08:11:25 +1100
> -----
> Just a curiosity question. What does the relay actually do?
>
> Regards
> Michael Foreshew
> SAP Practice Manager
> HiServ Australia Pty. Ltd.
>
>
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