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  #1  
Old 03-13-2014, 06:10 PM
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walkman walkman is offline
 
Join Date: Oct 2011
Location: Atlanta
Posts: 875
Default What relay for remote starter switch?

I have an unused pushbutton switch on the Infinity grip in my -8.

I would like to wire this switch to the starter so that I can have HOTAS for starting (currently ACS mag switch). I'm sure I will need a relay to do this as I think the Infinity has 24 awg wiring.

I was going to have a look at what AutoZone et al might carry, but does anyone have a recommendation to save me the trouble?

Thanks
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Old 03-14-2014, 05:28 PM
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UnPossible UnPossible is offline
 
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Location: Granbury, TX
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Default

I used a starter button from a Honda S2000 on my plane, which needed a relay.

I just got a black cube 12V relay from the local auto parts store... think it was $12 or so.. works fine...not a ton of current needed to pull in the starter solenoid.
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Old 03-14-2014, 05:41 PM
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vlittle vlittle is offline
 
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Starter contactor needs about 3 amps. Using a black cube automotive relay gives you the option of controlling both sides of the coil.

One side is connected through the pushbutton to ground and the other can be connected through a 'starter disable' switch to the master bus.

Don't forget to install a snubber diode or use a relay with an internal diode or resistor. Digikey has them.
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Old 03-14-2014, 06:32 PM
lrgabriel lrgabriel is offline
 
Join Date: Jun 2012
Location: Reno, NV
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First, I'm not an electrical engineer--this advice is only as good as the price you paid for it!

Second, please don't use crappy automotive relays--something with a datasheet and screw terminals would be better, an aircraft part even more so.

Third, about wire size...it never hurts to run the numbers. Assuming 105C rated, tin-plated MIL-W-27759 wire, not in a bundle, below 20,000 feet, ambient temp of 20C, and a 12 foot wire run including ground path...24 AWG wire IS sufficient for intermittent 3A loads. Reference AC 43.13-1B 9/8/98 Ch 11 figs 11-3, 11-4a, and 11-6. That said, I doubt your stick switch can handle a 12VDC 3A inductive load.

Last, I'm a huge fan of HOTAS, but make sure you do some thinking about locking out that switch--we lost a T-38 because someone's pants decided to activate the throttle-mounted speed brake switch.
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