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Discussion Starter #1 (Edited)
It's pretty easy to make Marx switches self tending using isolated rails. But it leaves the switches susceptible to coil burnout. So I devised a solution using a delay relay module. Once powered the module will trip it's relay after a delay - selected by a trim pot on the module. The isolated rails are connected to the straight and diverging route switch contacts as in the simple solution. But the accessory power goes through the delay module's normally closed connection relay connection. When a train connects the isolated rail, it also powers the corresponding switch coil. The delay relay module is powered up by the isolated rail connection at the same time and begins it's delay countdown.

Once the delay expires, the relay trips and the normally closed connection is opened disconnecting accessory power from the coil. After the train passes, the delay module powers down - reset ready for the next cycle.

The delay module has two LEDs. The first, visible in the video, shows the module powering up each time the train connects the isolated rails. The second LED, hidden by the module's components, shows when the delay has expired and the relay has tripped. In the video, that LED can be seen as a reflection on the modules blue relay. Notice the short time between power up and relay trip. That's the length of time the coil is energized.


Connections.JPG Module.JPG Delay Relay Approach 2.png
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