# What is needed to run an A/C FA B-unit w/ an A that already has Airwire?



## fredstrainshop (4 mo ago)

I have an Aristo Craft FA A-unit with AirWire G4 Decoder along with Phoenix P8 Sound and have a matching B-unit that is stock. What is needed to run the B unit with the A? I'm not concerned with additional sound in the B nor using the smoke unit. Just to run it with the A. I've gotten a couple different answers from people here in town but neither have actually done it so I thought I'd ask the experts.  Any help is greatly appreciated. Thanks!


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## Paul Burch (Jan 2, 2008)

A little more info would be helpful. What I'm getting is that you want to run both locos off the same A unit decoder. Question, do the locos have the two wire power plugs sticking out by the couplers?


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## Greg Elmassian (Jan 3, 2008)

If you are always going to use them together, just run all the motors from the G4. Note that a G4 has a maximum rating of 8 amps at 15 volts.

So, you should be fine unless you are subjecting the locos to something very stressful, 4 amps per loco will over time tear up the gears (you can only get there with a very heavy load).

So, I would do it with the single decoder and dedicate the B to the A. If you are using incandescent bulbs, do not hook them to the motor output of the decoder, and remember the max headlight current is 1 amp, and is not short protected (means be careful).

Greg


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## rogern (Sep 5, 2016)

fredstrainshop said:


> I have an Aristo Craft FA A-unit with AirWire G4 Decoder along with Phoenix P8 Sound and have a matching B-unit that is stock. What is needed to run the B unit with the A? I'm not concerned with additional sound in the B nor using the smoke unit. Just to run it with the A. I've gotten a couple different answers from people here in town but neither have actually done it so I thought I'd ask the experts.  Any help is greatly appreciated. Thanks!


I have an Aristo FA A and B unit running off the Airwire in the A unit. I slaved the B unit to the A unit by disconnecting the power pickups and then wiring the motors out to a connector over to the A unit. Works great. (Just make sure that you verify that the wheels are running the same direction on both locos...it gets exciting otherwise.)


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## fredstrainshop (4 mo ago)

Paul Burch said:


> A little more info would be helpful. What I'm getting is that you want to run both locos off the same A unit decoder. Question, do the locos have the two wire power plugs sticking out by the couplers?


Correct. Using them together as a single unit. And they do not have any power plugs at the ends.


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## fredstrainshop (4 mo ago)

Greg Elmassian said:


> If you are always going to use them together, just run all the motors from the G4. Note that a G4 has a maximum rating of 8 amps at 15 volts.
> 
> So, you should be fine unless you are subjecting the locos to something very stressful, 4 amps per loco will over time tear up the gears (you can only get there with a very heavy load).
> 
> ...


Yeah they will be used together. The A-B set would be pulling 5 or 6 aluminum Aristo-Craft passenger cars (the shorter 60' or so cars). Track is pretty much level so aside from the weight of the cars there wouldn't be too much load on them. So if I just splice in a pair of wires into the motor wires going to the G4 in the A unit and maybe have a plug hanging out the back and a similar set up from the B it should be fine? ...making sure of course the motors are all running the same direction. I just wasn't sure if a single battery in the A would be enough, etc.. I'll have to double check the lights on the A. Thanks for the reply!


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## fredstrainshop (4 mo ago)

rogern said:


> I have an Aristo FA A and B unit running off the Airwire in the A unit. I slaved the B unit to the A unit by disconnecting the power pickups and then wiring the motors out to a connector over to the A unit. Works great. (Just make sure that you verify that the wheels are running the same direction on both locos...it gets exciting otherwise.)
> 
> View attachment 64427


Thanks! That's what I was wondering. I was concerned if I needed and extra battery, etc. Will do!


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## Paul Burch (Jan 2, 2008)

Be sure to disconnect the power pickups in the B unit like was earlier stated.


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