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A different fuse.

The technology used in the circuit breakers for aircraft has been around for as long as I can remember and I remember when they invented salt.  I am using what I believe is a better mouse trap.  What I am using is a solid state device.  It is a positive temperature coefficient (PTC) thermistor.  It has no moving parts, doesn't arc on interruption, acts faster on overload and can be reset in a fraction of a second.  I have attached a circuit diagram that shows the way I protect branch circuits.  Physically, the two LEDs are mounted above a rocker switch.  The green LED lights when the switch is turned on.  In the event of an overload, the PolySwitch turns off causing the green LED to go out and the red flasher LED to flash.  Cycling the switch off and back on will reset the breaker.  Unlike the push button type breakers, you cannot hold this one in and set your plane on fire.

All these goodies can be obtained from Digi-Key (1-800-344-4539)

LED flasher  LT1042  $1.25 ea.
LED 12v green  MR3451QT  $.45 ea.
PolySwitch  RUE900  $1.47 ea. (9 amp. hold, other values available)

For those of you that are using an IVO in flight adjustable props, I would recommend you add the RUE900 device in series with the current thermal breaker supplied by IVO.  I ran some static tests to compare the mechanical breaker to the solid state device.  The solid state device trips quickly enough to cause less than half the compression of the plastic stop washer.  I ran the prop from stop to stop several times and the solid state breaker performed flawlessly.  The supplied breaker was still in the circuit and never tripped during the testing.  I think that is the cheapest protection you can get for your IVO gears.


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