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Switch Lighting Question
Jim models HO and asks:
“I am using #200 Atlas snap relays and am trying to figure out the specs needed for green and red LED’s and the required resistors for each. I understand it is best to connect the 2 LED’s and appropriate resistor in series? I would appreciate any advice as I have never done this before. Thanks!”
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If you use 12-14V DC (Not AC) and regular LEDs (Not super bright) use serial resistor 750 Ohm – 1kOhm. If you connect two serial LEDs and resistor, the value should be 600 – 800 Ohm. Better to use same LEDs in line.
Resistors must be connected in series with the LEDs. The value that I use is 1000 ohm. You could go down the 480 ohm. If you go to the website “wiring for DCC” you should be able to get all the information that you need. It is also written so that the novice can understand.
You can also calculate the resistor value with the Vansoft calculator tool. It is a free app that can be downloaded from there web site. There is a total of 6 different tools that can be used.
You can use AC on a LED by adding a small signal diode. I have been using LED’s on 18V AC in my Marklin train set which is a AC setup. The problem with LED’s and AC is the reverse voltage on the negative cycle of the AC wave. By adding a small signal diode in parallel the the LED you are clamping that voltage to 1.5V well in speck of the LED reverse spec.
LED-SWITCH.COM has red/green leds (all in one bulb) in lots of sizes they will send the correct resistors. I just ran mine with individual wires from the power source works great.