2007-08-11

Stationary decoder

In order to switch some light circuits utilizing an old loco decoder I took an old Märklin 6080 decoder and mounted it on a small board that can be plugged into the digital signal and have two independent light circuits plugged into it.


To each output I added a diode to ensure that stray current could not go the wrong way and also a 100µF capacitor to smooth the current out.

I Initially tied both motor outputs together and both function outputs together so that no matter what direction the decoder is in, the outputs will work.  However, if the decoder is set to go forward the blue (motor reverse) wire still gets some pulsed output, and if set to go in reverse, the green (motor forward) wire also gets some pulsed output.  Since the motor outputs are never off, the capacitor had the effect of maintaining power no matter what direction and speed was set, even at speed step zero!  I therefore decided to dedicate this decoder module to reverse-only output. This entailed cutting the gray and green wires. The picture above was taken before that cut.

This means that by default, when the layout is powered up, neither output will be on. This suites me fine for what I intend driving with this decoder.

The motor output  produces 17V no matter what speed step is used. (The capacitor effectively removes the pulse modulation. Under load I may see flicker at low speed steps.)

The function output produces 12.3 Volts.

I can now solder lighting circuits onto the gray plugs, each with the appropriate resistor for the LEDs in the circuit and the supply voltage. I just have to pay attention to the polarity since the plugs I had are not polarized and will allow incorrect insertion.

I have already prepared my software for driving any events using a loco decoder and this is what my event definition screen looks like for this decoder:

It will leave the function alone, setting a high speed-step, backwards. After 20 seconds my thunder sound effects will be played.

To switch the function output I define another event as follows

This will switch the function on and leave the speed alone.

Similar events can be defined to switch the outputs off.

Event definition user interface Copyright Dale Schultz 2007.

Additional use of a stationary decoder to drive a signal