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How to Wire Double-Throw (DPDT) Switch
Lester model N scale and asks readers:
“I like to know how to wire a DPDT switch. I own a DCC system NCS. I want to make a section on my main track as a program track. It is isolated from my main track. What I need is a diagram on how to wire it so that the program track becomes a main track when it is thrown on and the other way the program track has power and the main doesn’t.”
5 Responses to How to Wire Double-Throw (DPDT) Switch
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The easy way is to tap the isolated programing track first from the power buss. Then the power buss feeds a DPST switch. After the switch, the power buss feeds the rest of the main track.
The best way to wire your switch is to put the DCC bus wires to the two center contacts of the switch and then on to the programing track from the two center contacts. then from one end of the switch to your main line so that when the switch is thrown one way the programing track is live and the other way the programing track and main track bus is live. make sure the programing track has insulated track joiners so that power cannot feed the main line. The programing track will be live when the power is switched on but you can now isolate the main line. I hope this helps
As I understand, you want to isolate the DCC programming track from the Main-Line track for programming. But want to incorporate the programming track back into the Main-Line track when done programming. Here is an image that will do that for you.
Simple to wire the switch itself You have 2 center wire posts and 2 on each end . Feed you main power to the positive and negative of the 2 center posts. then feed the same side of power from one set of end pins to go to the program track. then feed the 2 on the other end to your regular buss wires for the layout keeping the positive all on one side of the switch and the negative on the other side. Ensure you know which end goes to the layout and which goes to the program track and mark your switch as such. You don’t want to do a program change and you sent it to the tracks with all your engines are on. I have the same switch hooked up on mine and since the switch is not mounted to the board yet I have to double check if I am on the program track.
Sometimes you might want to have a DC power on one side and DCC on the other to use the same program track to check a standard DC engine. Although it can easily be done I don’t recommend it as you will almost always forget which system you are on and could mess up an engine.
to wire a DPDT switch to reverse power for a route that needs to change polarity to get on the other track for instance of which I have one case like that. Feed from your buss wires to the center 2 posts. Your outbound wires to the track feed to one side pair of posts then cross over to the pair on the other end of the switch. It will look like an X with the wires from one side of the switch to the other. from Newman Atkinson
Thank you for all your help. I gave up on the switch coz I got it wired. When I would take the train on the main line then go on the isolated track and switch in the right position it would stop. Then I would have to start it up again. That is why I gave up on the switch. I will program the loco on the main track with out other locks on the tracks.
Thanks again
Lester