someone972

iTrader: (2)

I'm going to be re-purposing a 91 style defogger switch to be the actuator for an electric cutout. As such, I was wondering if anyone knew the amount of amperage the defrost switch will handle. I measured the cutout and it draws 0.01 A during regular travel and a hair under 0.5 A at full lock. It comes with a 1 A long blow inline fuse. Will the defrost switch handle this or should I put a relay in just to be safe?

EDIT: Scratch that, I'm an idiot and forgot to look up the circuit diagram first. I'll have to do a relay circuit anyway to be able to switch properly given the inputs/outputs of the switch.

Mods can delete this thread if they want, it serves no purpose now

sofakingdom

iTrader: (1)

The switch handles only a very tiny current. I'm surprised it's even as much as 1A. I'd have expected maybe a tenth of that.

The relay (relay = electrically-operated switch) handles the actual defroster current, which is some tens of amps. (30 or 40, something like that) The switch operates the relay via its coil, which then locks to itself through a timer. That way you push the button, the button sends current to the relay coil, the relay operates, its contacts send power to the actual defrost element AS WELL AS to the timer which is in series with the coil, when the timer times out it breaks the connection to the coil, the relay drops out (the whole system goes back to sleep), it is now ready for the button to be pushed again.

Yes you HAVE TO use a relay. The whole plan doesn't work without it. Besides, the switch and its wiring is ENTIRELY too small to power the heater element.

If this is an exhaust cutout, I'd recommend STRONGLY against messing with that. WHOLEHELLUVALOTTA maze, very close to zero cheeeeeeeze.

someone972

iTrader: (2)

Don't worry, this circuit is completely separate from the defroster circuit. Just needed a defrost switch for the momentary press both directions. I'll probably end up using a solid-state motor driver as opposed to a relay since I would need two relays in order to provide bi-directional control. It'll be a while before I get all the components together, but once I do I'll probably post up a thread about it since it should be pretty cool