April 27, 2015

Crossover indication with DTL logic…

Over on TheRailWire, someone asked if it was possible to create a circuit for indicator LEDs to properly show the crossover route if an only if the turnouts were both aligned using only the half of the DPDT contacts on the turnouts.  Here's a quick Diode-Transistor logic circuit which would use jelly bean NPN transistors (2N2222) to create a simple logic gate for the crossing route:

Both Turnouts "Normal"

One Turnout "Thrown"

Both Turnouts "Thrown"