I want to get some bulk LED packages, I know if I use AC power I will have to use a full wave bridge rectifier. If I use track voltage, I am going to have to reduce the power, hence the resistor. So what size would you use and does it make any difference if for a 3mm or 5mm LED? As an example, putting lighter marker lights in passenger cars or cabooses....
Thank You,
Marty
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Hi, Marty :
Try using a 470 K Resister first.
Marty, You can also try using a rheostat with a ohm-meter attached by rising and lower the voltage to you found the right lighting type that your looking for the train cars.
The ohm meter would tell you what size Resister to use.
Good luck, John
I didn't think you could measure ohms with power going thru it, I did it once by accident and killed all the ohm reading ability..
Marty
I just wired in 2 ditch lights in a MTH GP35. I used track power (18vac). From one side of track power>10k resistor>led + out that led- to the next led+ out that led - to other side of track power. Back to back LEDs act as your rectifier. Very simple. These are 3mm 15/20ma LEDs.
Get both sizes and some flat lens too. You only need one diode to use the ac. 470 ohms, not 470 k.
I'd use a 470 ohm 1/4w. To dim things like markers and class lights, you can go up in resistance, I've used as much as 2K for markers to they didn't come on too bright.
Would a 470 ohm 1/2 watt resistor be okay???
Marty
Sure, higher power is no problem.
Okay, thanks for all the info, now to get busy and put some LED's in my Flyer cabooses...
Marty
I use this wizard, I think Gunrunnerjohn originated it on the forum.
http://www.led.linear1.org/led.wiz
bruce
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