The Mystery of Electronics

[DUCKY01]

Jonathon,

The difference between the two PCB boards:

The slower locomotive is using 4 diodes to produce a voltage drop of 3vdc for the directional headlights, which are rated at 3vdc. This is 3volts that the motor never sees.
You jumped out the diodes when you ran jumpers from the truck pick-ups to the motor.

The faster locomotive is currently wired for Headlight LED's, or 12volt bulbs using a diode
for directional headlights. (one diode per bulb). You can either jump out the diodes, like you have done alread, or remove them and jump them out with small wires.

Scott

[jonathan]

Scott,

Thanks for the great info.

Since both locos now run at exactly the same speed, I will let sleeping dogs lie for now, if I am doing no electrical damage to the motor.  If/when I add decoders, then I can quickly remove my jumpers, and adjust the speed steps so the locos can MU together.  Hopefully, the lights will still work.  If I understand (that's a big IF), not enough (or no) current is getting to the diodes to turn the lights on.  That's OK with me. 

I suppose if I wanted to tinker some more, I could wire two temporary 12v bulbs in parallel.  I would have lights on in both directions, that get dim and bright along with the speed of the engine.  I gotta stop monkeying with these things before I break something.  Although, I do have a small bag of lift rings, just in case.

Respectfully,

Jonathan

[DUCKY01]

Jonathan,

Each diode produces a voltage drop of .75vdc, add another diode at that drops
another .75vdc, thus the two diodes produce a voltage drop of 1.50vdc. Add two
more diodes and that's another 1.50vdc. Four diodes together produce a 3vdc
voltage drop, thus your power pack is set to half throttle, but your motor is only
seeing 3 volts, thus the other 3 volts is being dropped across the diodes to produce
a directional headlight bulb rated at 1.5 volts. I use one diode (1amp, 50piv) and a
minitronics 12vdc bulb for the headlight, which only lights in the forward direction. If
you want a reverse headlight, use another diode, in reverse polarity of the first diode,
and another 12volt bulb. Since the diode only drops .75vdc, you will not notice any
difference in motor power. For DCC, each output of the decoder for headights are rated
at about 2vdc, so you can use small bulbs or even LEDs. (when using LED's, don't forget
to add a current limiting resistor to one lead of the LED!!)

Scott

[pdlethbridge]

Jonathan, If it ain't broke, don't fix it!

[Stephen D. Richards]

Jonathan,  actually I meant either or!  However, I learned more from this thread about those DC boards and may keep them for myself!  lol  Just kidding, if you need an older board let me know.  Although it sounds as if you've got a handle on this thing.  Maybe if I sent you mine....you could fix them.  lol   Stephen

[jonathan]

You know, it's funny.  All this tinkering has got me in good with my LHS.  When ever they get a return, or a loco that doesn't work (usually bumped too much in shipping), they let me fix it, and I get a small store credit.  I only do simple, obvious corrections, parts that are missaligned or lying loose inside the shell.  This is becoming too much fun, and keeping me from finishing the scenery on my layout.  Gotta knuckle down and make some trees and start lighting my structures. 

I love this hobby.  Glad I gave up golf.

Regards,

Jonathan

[Stephen D. Richards]

I'll second that!      Stephen

[CG04]

My wife told me it was time I started playing golf again.
That was on the way home from the Train Show.

Clif

[pdlethbridge]

uh oh. Someone's in trouble

[CG04]

PD,

I was in a touch of trouble until I took her out to dinner.  Of course, it didn't hurt when I explained that she had spent more than me.  She's getting into this train stuff and I love it.

Clif

[CG04]

PD,

I know this is "off topic" but, have you heard from Yampa Bob lately

Clif

[pdlethbridge]

no

[rich1998]

Here is a link to constant voltage lighting circuits. A single bridge rectifier that has four diodes drops the voltage 1.5 volts. I first saw this idea many years ago in a model railroader magazine.
A picture is worth a thousand words.

http://www.mrollins.com/circuit.html

Lex

[jonathan]

Lexon,

That's almost easy to understand.  I added that to my 'favorites'.  Thanks.

Jonathan

[NarrowMinded]

I just used a mircoelectronic's forward reverse light kit for daughters HO percy, She wanted lights. these units are around $14 bucks you could remove the boards from both locos and install new kits in both.

Just an idea,

NM