I'm putting in some hidden staging for my subway trains. I thought about using IR LEDs and detectors, but then I got fiendishly clever and decided to use reed switches activated by magnets in the trains. This is practical because there are only two trains that will ever be on that track.
I glued a small magnet to the underside of one of the powered units, and it seems to work fine. But, the thought occurred to me as I was trying to keep the magnet centered that the subway motor has a magnetic field of its own.
Is the addition of this small permanent magnet going to affect the performance of the subway motor? I've got it running now, and it seems fine, but is this putting any extra stress on the drive system of the subway?
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Unless you're putting the magnet directly under the motor, it should have no effect. I'd move the magnet to the bottom of one of the trucks if there's clearance there, instead of directly under the motor.
That's exactly how the signalling system on my layout works. I have had magnets mounted to the underside of about 40 engines for the last 15 years with no problems. The only thing I have found is that Proto mottors have a very strong magnetic field of their own and will trip reed switches without an additional magnet being mounted on the underside.
For an installation suggestion - mount the magnets somewhere on the truck itself to they remain centered between the railheads. I tried the fuel tank, but on longer engines, the the tank would be off-center in curves and not always trip the reeds.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I mount my magnets on the right (engineers side) of the loco. This gives me directional control in return loops/signaling etc. I have not encountered any reaction of the motors. The only loco's that have to be handled different are yard switchers that may enter a section from either front or back. I feel the cost savings and ease of applications is much greater than IR. I acquired a bunch of reed switches free so I may be swayed a little in this direction.
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