Reversable lighting...

[shaygetz]

I know I've got this in my stack of old MRs but I can't seem to find it. There are two simple circuits I'm looking for. One is the diode reversing light circuit and the other is for constant intensity brightness. I'm opting out of the DCC movement on my layout for now and so I'll need these circuits to help my locos lighting look better. Thanks for any help.

 

[Fred_M]

Here's one, just add more diodes for higher voltages. (aprox .7v per diode (pair)) Fred

 

[shaygetz]

Thank you, Fred. I'm assuming that the red and black are + and - ?

 

[Ray Marinaccio]

This is a constant intensity directional lighting circiut with nondirectional markers that uses LEDs for the lights.

 

[shaygetz]

Thank you, Ray. I can read schematics pretty well, are those diode symbols?

 

[Fred_M]

Thank you, Fred. I'm assuming that the red and black are + and - ?

No, you cut a motor lead, the red goes to the wheel side and the black to the motor side. The first diodes provide directional and are really not needed with LEDs, but you didn't say what you were using. If your using LEDs, Ray drawing is the same circuit. You are using the voltage drop across a silicon diode to provide voltage drop which can be used for power. Most LEDs will need 4 each way to get about 3 volts. There are other ways but this one is cheap. Fred

 

[Ray Marinaccio]

Yea. Those are crude diode and LED symbols.
The circiut is actually a bridge rectifier with the AC terminals hooked in series with the motor and three diodes in series hooked between the the + and - terminals of the bridge rectifier.

 

[shaygetz]

Thanks, Fred and Ray, it's been a big help. Is there any specific value to the bridge rectifier? I still might have a question down the line if I see any magic blue smoke I love electrical stuff but I'm not as knowledgable as I'd like to be.

 

[Ray Marinaccio]

I would use a bridge rectifier and diodes that will handle as many or more amps than your power supply circuit breaker.
I used lighter diodes on one and had an accidental short across the motor, it fried the diodes which in turn put 12 volts across the LEDs. Toasted all of them.