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Model Rail

Track Priority Switch with Indication

In this example we are using a 3PDT (3 Pole Double Throw) switch to control 2 separate Layouts or Tracks from one Speed Controller, with an LED indication back at the Control Panel, indicating which Track / Layout is Active.  This switch will work just as well on DCC as it does on an Analogue layout. Each track is switched through the toggle switch as shown using terminals 1 to 6. The Indicator LED’s us the terminals 7 to 9, and are powered by a separate Power Supply at 12v to 5v. A Dropping Resistor of 1K is required for the LED’s which can be fitted on the Negative 0v wire. The Negative 0v pin on the LED is the short Pin. The switch has a centre OFF position which can be used if you want. You can get just a straight forward ON – ON if you prefer.
In this circuit the Indication has been replaced with a Bicolour LED, which means we have to change the 3 pole switch to a 4 pole switch, so that we can use the switch to reverse the polarity for the LED. The wiring of the Track A & B is exactly the same on this switch. The difference with this switch is, it does not have a centre OFF position. This means that either Track A is live or Track B is Live. You could, if you wanted have a centre OFF switch.