LED H/L problem

Where are the LEDs from?  What kind of engine/electronics did you install into?  Is these at command-voltage levels or lower conventional voltages? 

Details on what you have/did will get you a better answer.  

Stan,

THe LEDs are from Minitronics, I installed them in a 2Railed K-Line Plymouth with resistors running on straight 12vdc.

Thanks, Malcolm

Without playing 20 questions, if I had one chance at a fix, it would be to connect the LEDs back-to-back in "opposition" as shown.  Then use 1 resistor to connect to track voltage.  You might be able to try this fairly quickly by adding a few bypass jumpers to your existing wiring.

Or if you want to continue with the Q & A, my next question would be what do the pair of LEDs do at lower voltages?

I'll modify Stan's picture a bit.  For pretty much 100% chance of success, I'd wire the LED with a bridge rectifier first, then a resistor, and then the LED.  For 12V for a headlight, I'd use a 1/4W 470 ohm resistor for a white LED.

Is this one LED or two LED's in each end of the locomotive?  For two identical LED's, wire them in parallel and use a 270 ohm resistor after the bridge rectifier.

What's the purpose of the bridge rectifier if he already has a DC source??

When the DC source reverses in polarity, the LED DC supply remains constant.

Stan,

Thank you, I will try that. Malcolm

I thought the lights were to reverse.  One on in forward with the back light off, the other on in reverse with the front light off, via reversing polarity ??

It's not clear what he has, so I was presenting an LED that will light on any voltage AC or DC and any polarity.

I wonder if this blinking is by design?

anybody got one still stock?

I will draw a diagram of my wiring and post it shortly. Thanks, malcolm

That circuit is for 1.5V incandescent bulbs (not for LEDs).  When the DC motor is spinning on one direction the 2 silicon (1N4001) diodes "drop" about 1.5V and the bulb sees the same and lights up.  In the other direction, the 1 Schottky (1N5817) diode drops less than 0.5V so the bulb does not light up.

Edit: just occurred to me that that circuit was probably intended for HO.  Those are 1 Amp diodes so undersized for O-gauge traction.  So if going with incandescent bulbs for directional lighting, choose silicon and Schottky diodes with higher Amp ratings.

One question I have is why the original installation had a blinking LED in one direction, that seems more than a little odd.  I guess I still don't understand how that is happening.  There has to be something triggering that behavior.

If this is a plan DC locomotive and you're wanting directional LED lighting, I like Stan's simple LED circuit direct to track voltage.  You have to reverse polarity to reverse direction, that's all it takes. 

Thank you guys! This is what I have but I am going to change it to Stan's diagram tomorrow. Sorry it took me a while, had to wait until all the company left.

I told you I am very electronically challenged.

Malcolm

Another thing that will help the flickering issue.  Use a 47uf non-polarized cap across the LED pair after the resistor.  Your connection and Stan's are very similar, you just used two resistors.  The big benefit of Stan's connection is the two LED's protect each other from excessive reverse voltage.