MODEL RAILROADING with   LAURIE GREEN

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MAIN & LOCAL

TURNOUT CONTROL

If we have a central control panel for our railroad, but still want to be able to allow a local operator to change a turnout, how to we do it. It would also be important that the central controller know if the turnout had been changed by the local operator.

This is not a difficult system to achieve. What was needed was a split power supply which I could control the voltage output. The solution – an old H&M ‘DUETTE” transformer with two controllers.

 

To obtain a controlled split power supply from this unit, turn the control knobs to forward, and with a multi-meter find out which of the two of power outlets on the back are the negative ones. Then bridge these two outlets. This becomes the common or zero voltage supply and is wired direct to the motor. Turn one of the front knobs to the reverse position. You can now adjust the forward and reverse knobs to obtain the exact positive and negative voltage required. About 8 volts seems to work best for this application, but different turnout motors may require different voltages. Trail and error is the only way of finding out.

 With this split power supply, we can tap a central 0 volts, as well as a +12 DC volts maximum and -12 DC volts maximum. We will also need a push button double pole double throw switch, a push button single pole double throw switch and some coloured LED's (and their appropriate resisters - normally I use 3mm green LED's and 560 ohm resistors)

 

Below in diagram 1 is the wiring and switch locations for straight through on the track plan, as well as the panel LED indication. Diagram 2 shows the configuration when the turnout is switched at the local panel for the curved track The two grey boxes on the right are the facia of the panel. Click on the thumbnails below to see the diagrams.