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Old Hornby dublo control unit.(A3)
Getting things started now for new lay out after 40 odd years. Sarah answered one of my questions,now for the next. Three postions on the front of the power unit ( A3) A-B-and C I know A is for the track but need to be sure what the other two are used for I think one is for points, if so can I run two points off one outlet. Do I need two units if I run two trains.
Thanks for taking time to read this and I hope I can get some results
Dennis
 

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Output B is a constant 12 volts dc that will supply 10 watts. Points are operated using a 'passing contact' switch, meaning that the supply is not permanently connected, therefore you can operate as many points as you wish.
Output C is 15 volts ac and will supply 15 watts. This can be used for other accessories such as lighting.
You will need a controller for each loco, not on the same track of course.
Hope that helps if you are still logging on here as your query is a few days old now.
 

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Dragon Trainer
Currently residing at Dragon’s Edge, living on The Edge! 😀
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Hi Dennis.

I can now confirm that HD 3-rail electric points are the same, motor wiring wise, as 2-rail ones in that the "centre" terminal is the common return.

As said above, the points only use power "momentarily" while they are actually changing. HD points can be run from either the 12Volts or the 15 Volts supply. (The higher voltage is the one normally used, as it gives the solenoid more of a "kick". BUT it does mean that you have to be a little more careful when using the switches, that you do not leave the lever "on" too long and "cook" the windings of the solenoid!)

The 12Volts "uncontrolled" output is the one that can be used by the (as Tri-ang call it) circuit controller to control a second train on a separate circuit. Marhsall (Meccanno )units were available for this purpose.

I should have more info in my files, I will look into it and post again!
 
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