# Aristo Rev TE and USAT SD70



## ekaeric (Apr 10, 2009)

I have been installing a Rev TE Receiver in my USA trains SD70. So far all I have left to deal with are the ditch lights but I am not sure if the following issue is possible or not. Because the track now has constant power the ditch lights are on constant, normally they alternate up to about 10 volts then are on constant after that with a normal DC linier track power (cool effect see video with straight DC below)). I am not sure how to wire them so they can maintain that alternating flash then constant power. I have figured out how I can either regulate them and have them alternate or have them on constant but can't figure out both like it was with the straight DC. Because the motor outputs on the rec are PWC, I cannot connect to those outputs and get the linier voltage increase needed to the stock circut board for the alternating flash and consant power circuitry. Any ideas on how to get a linier voltage to them with a PWC motor output? Thanks Eric


http://www.youtube.com/watch?v=aHrAVnZ2Srs


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## Del Tapparo (Jan 4, 2008)

Eric - I would go ahead and connect the motor outputs to your circuit board. If it doesn't operate properly, you can try adding a capacitor across the input to the board. The PWC (I'd rather call it PWM: Pulse Width Modulation) is linear. All it needs is a little filtering to make it act just like DC. Most circuit boards will already have the filtering.


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## Greg Elmassian (Jan 3, 2008)

Del, if he adds a cap across the board to the input, isn't he actually placing a cap across the motor, and the TE output? 

If so, won't that reduce the effectivity of the PWM from the TE? 

Because they should only operate in forward direction, couldn't he isolate the ditch light input with a diode? 

Regards, Greg


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## ekaeric (Apr 10, 2009)

Thanks Del. I have actually tried hooking up the wires briefly to the motor control and the problem is that all the lights do come on but the ditch lights are also on 

constant and not alternating. Greg you are correct they do only operate in forward only. Hooking up the board to the motor output is basically the same result 

as when you connect the board to the track power input solder pads on the TE rec. As soon as you click up the throttle one step the lights and ditch lights think

you are at full power. Normally this is good but the ditch lights pass the alternating phase and go right to the constant phase. I like the fact that the board when 

connected to the track power pads has 22volts this makes for a good smoker, cab and marker lights at low speed and is easy because it only leaves the one thing, 

ditch lights to deal with. Greg has given me an idea and that is to somehow isolate only the ditch lights and maybe tie only those to the motor pads with 

appropriate diodes to keep them efficiant. The trick will be to find out how to tap only into the ditch lights. I'm just kinda thinking here out loud so any ideas are 

very welcome. Eric


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## Greg Elmassian (Jan 3, 2008)

You got my idea Eric... isolate the power to the ditch lights, feed from the motor leads with a diode in one wire to isolate. Then an electrolytic cap should average out the pulses to give you "real" dc for the ditch lights. It should work... 

Regards, Greg


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## ekaeric (Apr 10, 2009)

Its a great idea Greg, except I am having a hard time finding where to intercept the ditch light power. It looks like the cab and marker lights are intergrated into the ditch light circuit. It looks like they have put in a voltage regulator for the lights. They all put 4.63 volts when I add 22 volts to the board so I am assuming the voltage regulator looking thing on the board is for the lights. There is only the one. I have a father in law who is a electronics repairman maybe he can look at the board and find a way into the ditch light circuit. I am at a loss I have been carrying that board around for the last couple hours looking at it. I will figure it out but not sure when. Eric


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## ekaeric (Apr 10, 2009)

Just out of curiosity Greg would these ditch lights be an issue if I were running say an NCE DCC system or any DCC system for that matter and trying to install a decoder in this engine? I would imagine the track would still be powered and things may need to be seperated. Do the decoders use this PWM? Thanks Eric


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## rpc7271 (Jan 2, 2008)

I am waiting until QSI comes out with their replacement board for the SD70. Ideally you can replace the old board in the SD70 with theirs and then plug in the Rev board and the ditch lights should work correctly.


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## ekaeric (Apr 10, 2009)

[No message]


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## Greg Elmassian (Jan 3, 2008)

All current DCC decoders use PWM to control the motor. The problem you have is that PWM fools the Aristo circuitry as to motor speed. You either try to convert the PWM to "analog dc" or run the ditch lights from a function output on a DCC decoder, and use the "brains" of the decoder to do the flashing and speed sensing. 

I gave you the "easier" way, but it might not be easier if you have trouble isolating the circuitry. Another option is to buy a FL-2 decoder and run the leds for the ditch lights from it. 

Regards, Greg


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## ekaeric (Apr 10, 2009)

I found a way to isolate the ditch lights but will have to continue to try to find a way to get analog Dc to the circuit board from the motor outputs. Thanks For your help Greg. Eric


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## ekaeric (Apr 10, 2009)

I have the solution it sound like a lot of work but is not. Lewis Polk cleared up the actual use of those aux wires and their limitations. I knew they were for

sound but was hoping they could be used for more. Lewis gave me a great idea about the smoke boards and to use them as a relay for other functions. I 

have come up with a solution. I will power the first smoke board with track power so it always has power to turn on and off lights. When I turn it on with an 

aux wire it will feed the PC board with 22 volts only I will either regulate it or use a resister to bring down the voltage to the point the ditch lights alternate.

This will also turn on the cab lights. The second lead of the first smoke board will plug into the power connection of the second board. The second smoke

board will allow power around the regulated power of the first board to the PC board and power the ditch lights on constant. This will allow me to use the

factory circuitry for all functions as intended by just switching the voltage. This is also good because the ditch lights will have a nice initial power for the

alternating sequence unlike regular dc power. So here is what happens. I push button 4 the cab and alternating ditch lights come on though the first smoke

unit and puts power to the second. As I speed the train up I hit button 5 which activates the second smoke board and gives the PC board full 22 volts the

lights go to constant and we are good. As I slow I turn off button 5 and as I stop, turn off button 4 lights out. The good thing also about using the stock

board circuitry is that when I switch to Reverse the stock board circuitry shuts off the ditch lights so if the locos turned around or I go into reverse the ditch

lights go out. This will only use two aux wires. Thanks Everyone, Eric


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