Ground Signal Control

[GrahamU]

I have recently purchased several DCC Concepts ground signals that I was intended to control using Gaugemaster G500 latching relays (to be activated by the point motors). I now find that the signals only have two wires but the relay has 3 outputs. I have a separate 12v DC power supply for the signals . How should I go about wiring these? Is it even possible ? It is essentially just a matter of using the relay to change the signal polarity but the solution is not obvious to me!

[Brian]

Hi

See the wiring below for the DCC Concepts shunt signal and the GM500.

Note:
You MUST fit the resistor (failure to fit it will blow the LEDs immediately)
The power supply should be 9 to 12 volts DC and regulated.
If the shunt shows opposite aspect for route swap wires on GM500 pads 1 and 4
The GM500 cannot be used for any other switching functions i.e. Frog polarity.

[GrahamU]

Thanks Brian.
How critical that the resistor is 5k ? The shunt signal is supplied with several resistors, 7.5k, 10k and 15k.

[Brian]

Use any of those in that group in place of the suggested 5K..... Suggest you start with the 10K, If the shunt LEDs are are too bright use a higher value resistor if to dim use a lower value.
The DCC Concepts web site quotes a 5K resistor. Rather unusual that they supply three different values. Is there any explanation in the leaflet/manual as to why they do this? e.g. Use xx Ohm value for one specific voltage range and use anther value for a different voltage???

[GrahamU]

They include several different resistance values simply to provide a choice of lamp brightness.
I guess this depends on the period being modelled - for those that are really particular!

[GrahamU]

So this is my effort at wiring up each relay - quite a lot of fiddly soldering required!


After fitting four of these to their associated points and signals, none of the relays would work. A careful re-read of the Gaugemaster instructions indicated that when using a CDU power source, the polarity of the input signal is critical. A simple swap of the output wires from my CDU solved this and now everything works as intended.