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TonyDuell · 14th May 2019, 6:31 pm

The older way to do that sort of thing (which avoids microswithes in the buffers) was simply to cut one of the rails about a train-length from the end and connect a diode across the break. The diode polarity is chosen so that when the loco is running towards that end, the diode is reverse biased. So the loco runs over the cut in the rail and then stops (as the diode prevents the motor from getting any power).

The supply is designed to reverse periodically (a relay and a slow astable or something). When the supply reverses of course the motor starts again as the diode is forward biased. Do that at each end of the track with the diodes connected the right way round and you have a train that runs to one end, stops until the supply reverses whereupon it runs to the other end and stops, and so on.

14th May 2019, 6:31 pm	#9
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: A Trainorama ! The older way to do that sort of thing (which avoids microswithes in the buffers) was simply to cut one of the rails about a train-length from the end and connect a diode across the break. The diode polarity is chosen so that when the loco is running towards that end, the diode is reverse biased. So the loco runs over the cut in the rail and then stops (as the diode prevents the motor from getting any power). The supply is designed to reverse periodically (a relay and a slow astable or something). When the supply reverses of course the motor starts again as the diode is forward biased. Do that at each end of the track with the diodes connected the right way round and you have a train that runs to one end, stops until the supply reverses whereupon it runs to the other end and stops, and so on.