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 Wiring Headlights for Decoder with only DC
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jburch
Engine Wiper



Posted - 02/23/2019 :  8:40:04 PM  Show Profile  Reply with Quote
I'm repairing a On30 Railtruck for a friend. The circuit board was toast as was the decoder. I have a decoder but instead of replacing the circuit board I am just going to hardwire the decoder right to the truck. The problem is I run everything dead rail so no DCC on my layout. I have the truck moving forward and backward perfectly using DC. Now the headlights and tail lights. I have the taillight working when the truck runs backwards but I haven't figured out the head light wires yet. Since the voltage is minimal when I use the transformer the LED are fine, but when my friend runs this on his DCC layout all the lights will need resistors, correct? I am using 1/4 watt 1000 ohms. do I need one for each light or just one for the headlights and one for the tail light? Should the resistor be wired to the common lead on the decoder or one to the white and one to the yellow for the headlight and taillight respectively? Last question is can this be tested on just a piece of track hooked up to a DC transformer.

Edited by - jburch on 02/23/2019 8:41:43 PM

Country: USA | Posts: 331

desertdrover
Engineer



Posted - 02/23/2019 :  9:22:06 PM  Show Profile  Reply with Quote
quote:
Originally posted by jburch

I'm repairing a On30 Railtruck for a friend. The circuit board was toast as was the decoder. I have a decoder but instead of replacing the circuit board I am just going to hardwire the decoder right to the truck. The problem is I run everything dead rail so no DCC on my layout. I have the truck moving forward and backward perfectly using DC. Now the headlights and tail lights. I have the taillight working when the truck runs backwards but I haven't figured out the head light wires yet. Since the voltage is minimal when I use the transformer the LED are fine, but when my friend runs this on his DCC layout all the lights will need resistors, correct? I am using 1/4 watt 1000 ohms. do I need one for each light or just one for the headlights and one for the tail light? Should the resistor be wired to the common lead on the decoder or one to the white and one to the yellow for the headlight and taillight respectively? Last question is can this be tested on just a piece of track hooked up to a DC transformer.



Some people get away with putting one resistor on the blue function lead for both lights. Stay away from that practice, and get used to hooking up a resistor for each light. One on the forward white wire, and one for the reverse yellow wire. 1/4 watt 1000 ohms is always a good safe choice resistor. We could get into a lot of tech talk on the best resistors to use when and where, but that's not needed. Go with your 1/4 watt 1000 ohm. The lights could be tested on your DC at minimal voltage, but it isn't going to work the decoder.
If you are running wires to both headlights, you can get away with one (1) resistor on the white lead, then splitting off to both headlights.
Remember this thread?; http://www.railroad-line.com/forum/topic.asp?TOPIC_ID=50266#838608




Louis
Pacific Northwest Logging in the East Coast
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jburch
Engine Wiper



Posted - 02/24/2019 :  1:30:44 PM  Show Profile  Reply with Quote
Louis,

Yes I remember the thread. I have some of the diagrams printed out on my work bench. I just want to clarify one thing. I should sort out the wiring for the lights first with my DC. then add the resistors on the white and yellow wire after I have done that because they wont work once the resistors are installed with the decoder, correct?


Thanks for all your help.



Country: USA | Posts: 331 Go to Top of Page

desertdrover
Engineer



Posted - 02/24/2019 :  3:53:56 PM  Show Profile  Reply with Quote
quote:
Originally posted by jburch

Louis,

Yes I remember the thread. I have some of the diagrams printed out on my work bench. I just want to clarify one thing. I should sort out the wiring for the lights first with my DC. then add the resistors on the white and yellow wire after I have done that because they wont work once the resistors are installed with the decoder, correct?


Thanks for all your help.



Yes, you are correct.



Louis
Pacific Northwest Logging in the East Coast
Post count: 5000 posts added to below count.

Country: USA | Posts: 15000 Go to Top of Page

jburch
Engine Wiper



Posted - 02/24/2019 :  7:22:04 PM  Show Profile  Reply with Quote
Thanks Louis, everything went as you described. With each new task I tackle I learn something new and it becomes something I can use as well as pass on to others.

Thanks Again

Jeff



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