Large Scale Central

DEAD SHORT!

Electronics Power and Sound
#1

Hope that got your attention. I’ve built a battery car to power a small engine. The project is to operate a battery powered track cleaning train to clean the track so I can run my track powered engines and on-board lighting.

Before I added the speed controller, it worked perfectly using a Harbor Freight 12V LiOn rechargeable battery. And, for $7 I found a perfectly acceptable remote control.

But, how was I to know that the track was clean enough to run track power? I decided to install two LEDs on the rear car which would get power through the rails from the battery. Power from the battery would run the loco directly, and the power would pass into the rails, and back out again through wipers on the wheels. So far, so good.

When I wired it that way, I got the LEDs on, but the wire burned up! Is it just the wire is too small for the current? Should I use larger wire, or some kind of resistor to drop the 12V to under 9V? (The LEDs seem ok still. They’ve got a resistor wired into each LED, and the LEDs are wired in series.)

So, where’s the short coming from, and how do I un-short the circuit(s).

TIA

#2

hi

you need a current limiting device for LED’s.

search all electronics or your favorite electronics supplier for CL2N3

a 20 milliamp current limiter( looks like a transister)

Bill

#3

OOPS

i GOT THE CURRENT LIMITERS AT MOUSER ELECTRONICS

part number 689-CL2N3-G

Bill

#4

Dick did you try on hooking you main track power at the track? i have used just resistors with no problems. you did not say what size wire you used.

Richard

#5

It sounds to me like you are using your track as a giant buss bar.

Bad idea! That’s too much resistance for that little battery. The battery should power the loco’s motor only. The engine should be isolated from the track.

You can put 12 volt LED’s in the car and power them with a rechargeable 9V battery. They’ll burn brightly for hours.

#6

I think that somehow, I shorted things out with my “improvement.” Now I’m getting the lights on when the track is cleaning up, but I don’t see how I’ve got power to the LEDs.

Must be a phantom circuit in there somewhere. It’s working fine, and I can’t see that the LEDs are hooked up to any source of power.

BTW, I do use LED drivers in most applications. Love 'em. Get mine from Mouser, too. I’ve developed a power supply (using those drivers) to convert variable track power to unidirectional current, through the driver, to an unlimited number of LEDs.