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Anyone got a wiring diagram for the USA Trains PA-1 they can send me? I'm putting R/C in one at the moment, and I'd like to see if there's a way to preserve the directional LED functionality using the lighting outputs of an Aristo Revolution control. Worst case scenario, I yank the board and wire things directly, but I'm hoping to avoid that if possible.

Later,

K
 

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Kevin
The really easy way to do it is with a small DPDT relay, the coil of which is controlled by one of the lighting outputs. I usually use reverse as that means when the loco is running forwards the coil is not engaged. Saves little bit of the battery power. Use a small kickback diode across the coil. Banded end to +.
I then feed the traction battery voltage to one end of the relay and wire the relay to give a polarity change. The output of the relay is fed into what were the track pick ups. The lights are constant brightness and reverse with the polarity.
The motors of course are also disconnected from the USA wiring and are fed by the ESC output directly.
 

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The problem on most every USAT diesel with the "classification lights" is that it is a common cathod red/green LED. For easy use with normal decoders, since the "common" is positive, you need a common anode LED. To top it off, green would be a very unusual color to see. I changed a GP7 recently to use a white/red LED and to control it from DCC (same setup as the Revo) and have white, red or off.

The LEDs I found were 2 pin LEDs, not the 3 pin on the stock board.

If it was my loco, I would replace and rewire the lights, the green in forward looks goofy. I wired the cab and number boards on all the time, the headlights to be independent and direction dependent, with the top light as a mars light and the bottom one solid on.

Some details on my GP7 page.

Greg
 

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Discussion Starter #5
To top it off, green would be a very unusual color to see.
That's what I was thinking, too. How often did trains run as sections? (On the other hand--credit USA for choosing a color for their class lamps that's at least prototypical.) Thanks, guys. Methinks I'll head down to the workshop and play...

Later,

K
 

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Well, green means that the train is not only in sections, but that this train is not the last section... sections are pretty darn rare with diesels...

I guess at the time of the first design, the bicolor LEDs available were only red/green... from my early days with leds, red was the first color, and green the second developed.

I wanted the option to have no class lights on, but red in reverse is ok, although it was unusual to use class lights for the rear of a loco... normally they had a single aux red light separate, or in one of the headlights.

Regards, Greg
 

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Posted By East Broad Top on 12 Feb 2012 12:53 PM
Would that also turn the headlight and cab lights off when the Revolution is stopped? I'd prefer to keep those on all the time if possible.

Later,

K

Kevin.
I did say it was the really easy way. Not technically correct. However, I have never had anyone want to get that specific with the colours of tyhe LED's.

The relay does not control the lights. It controls the whole of the USA loco wiring. All the lights (and other accessories) will work as though they were on a constant track voltage. You can still trun off various items via the USA control panel
 

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Discussion Starter #8
Minor fly in the ointment... USA, for whatever reason, uses a single block of clear plastic for the class lamps, with the forward lens clear, the outside lens colored red. So no matter what color LED is lit, it shows red out the side. *grumble, snarl, snort* So, having the class lamps lit when going forward is out, since I don't want red lights shining out the side. (Which is fine from a prototypical standpoint, since they'd only be lit in rare cases anyway.) I decided that the "cut and gut" method then was probably the simplest way forward. So out with the old, in with the new. (Glad I bought a strand of warm white LED Christmas lights on clearance last month.) So now I've got the headlight, cab, and number boards all tied together, drawing their power directly from the battery. When the loco's on, they're on. (I generally like at least one "indicator" light somewhere on the loco anyway, be it a firebox, cab light, etc., just so I know the thing's got power.) The lights going to the class lights are tied to the reverse output of the Revolution. When the loco goes into reverse, these come on. I colored the LED with a red Sharpie so it shows red out the side and front, opting to leave the front class lamp lens at least looking clear instead of red.

My only "gripe" with the way I'm doing things right now is that the headlight remains on when the loco goes into reverse. There's really not a simple way with the Revolution to keep the headlight on both while in forward and stationary, but turn it off in reverse. (I'm open to ideas if anyone has some.) If this were my loco, I'd simply hook the headlight to one of the aux. function outputs and just turn it on and off at will. Since this isn't, and the owner wants to keep things relatively simple, I figured this was a fair compromise. After all, this is a PA-1, so if it's going backwards, it's doing some kind of switching move and the headlight would likely not be turned off in that instance anyway.

Thanks again for the help!

Later,

K
 
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