Oh! Go on then....do tell please

Please Do

Alan

The Approach Lights are out when the semaphore signal is ON and light up when the signal is OFF. If the next signal is at red the Approach Light shows Yellow and if at Yellow then the Approach Light is Green (in a three aspect territory). As soon as the semaphore signal is replaced the Approach Lights are extinguished.

To achieve these controls using DCC, I needed a decoder with a relay to switch the Approach Lights on and off. Having looked at what's available I selected the DCC Concepts AD1-HP intended to switch stall type point motors. Unfortunately the Relay output only stays energised for about 5 seconds, although the relay remains in the last state commanded. To overcome this problem I studied the PCB and worked out that by cutting the track with the timer circuit and bypassing it with a wire going from the contact straight to the output terminal, achieved the desired result. Needless to say this mod invalidates the warranty.

The signal now has two decoders with the same address - one for operating the semaphore motor and the other the AD1-HP to switch the Approach Lights on and off. The Approach Lights piggy back off the Decoder for the next signal.