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Author Topic: wiring switches and led's  (Read 4043 times)
John Honeck Sr

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« on: June 22, 2013, 02:43:30 PM »

Another wiring question. Can any one supply me with a wiring diagram showing me how to wire in switches and LED's on the control panel and to the following areas of the layout:
1) switch (SPST or Buchmann turnout switch provided?) on control panel with a BIPOLOR LED also on control panel, then wiring to the turnout.
2) switch (SPST or DPDT ?) on control panel to light (LED) also on control panel then wiring to the track.
One more question should these LED's have resistors wired into each of these applications?

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« Reply #1 on: June 22, 2013, 04:02:24 PM »


This gets a little complicated because you only have a momentary pulse of power to the switch machine. Wiring the two-color LED with the switch machine wiring would only flash the indicator and then it would go black. There are still ways to do what you want but they are more complicated than just wiring the turnout or some lights in a structure.

Many turnouts or switch machines have contacts which you can use to change your red and green lights. The convention is that green indicates the mainline -- most often the straight leg of the turnout -- and red indicates the diverging route. However, the sometimes tight clearance on model railroads means the diverging route might be the main. I suggest that you decide whether green will mean mainline or straight leg and then be consistent throughout your control system and panel. While this method does require running wires all of the way back from the switch machine it isn't confusing. You will wind up with a ton of wires behind your control panel.

Another way to do this is to use a relay right "downstream" from the switch machine controller switch to switch the panel lights. With power supplied directly to the two sides of the bi-color LEDs, the correct color will remain lighted until you throw the switch the other way. You will need to use resistors at each LED unless the power to your turnout LEDs is already at 4.5 volts (which is what I'd do to simplify things, save a little time and save a few cents.

The last option I can offer is to have a second switch for each turnout on your control panel so you throw one to change the position of the turnout and one to change the color of the panel light. This is probably the easiest, least confusing and cheapest way to go. Unfortunately, it is also by far the most Mickey Mouse and irritating way to go. And, you might wind up with a front page quality train wreck if you forget to toggle an indicator light or even if you remember but don't push the switch hard enough.

Bottom line? I'd go with a relay system. It will work with both DC and DCC and it will be more authentic than running miles of wire or having to throw two switches every time you change a turnout position.

Good luck!

                    -- D
Joe Satnik

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« Reply #2 on: June 22, 2013, 06:55:41 PM »

Dear All,

Tortoise machines have 2 extra SPDT switches that change with the position of the points. 

Also, the bi-color LED can be put in series with the Tortoise motor, which acts as a current limiting resistor for the LED.,14781.0.html

Hope this helps.


Joe Satnik

If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.

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« Reply #3 on: June 22, 2013, 07:43:40 PM »

Since you mentioned using the Bachmann  control boxes, I am going to suggest using an atlas snap relay in parallel with your switch motors. this device is activated by the same momentary burst of power as the switch motor, and has 2 sets of contacts which can be used for panel lights, lineside signals, or even to kill power to a siding when the switch is lined for the main. instructions on how to do this are packaged with the relay.

to use led's with this relay you will need resistors, but their value will depend on the voltage of the power supply you are using. also, if you are going to use bi-colour led's, use the ones with 3 leads. those have red and green led's wired internally to a common ground. thus, you have a green lead, a red lead and a common. the two lead led's are bi-polar, with the red and green led's wired in opposite polarities from each other. the only way to switch colours on this type is to reverse polarity, which greatly complicated the circuit.

Jeffery S Ward Sr
Pittsburgh, PA
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