Has anyone tried wiring one decoder for 2 locos?

[onetrack64]

Hello Everyone! I'm new to these forums, so forgive me if I'm not "doing it right".

My question is this. Has anyone tried to wire one decoder into a pair of MU'd locos (Say 2 GP9s)? With the low current draw of todays motors, I believe it could be done. I'd isolate and wire in just the motor on the second unit, and possibly the headlight on one end.

Any thoughts or recommendations would be great!

Don

[SpaceMouse]

Let us know how it works. Personally, I'd spend the extra $15 or so and get a second decoder. Then you can adjust the mu to make sure the locos are traveling the same speed.

[Anonymous]

I've seen it done, at a local club theres a Cow/calf set that operates on the same address, Im not sure how the owner does it, but when you call the locomotive up (I believe its something like #1076 and #1076b both the cow and the calf react.)

[SpaceMouse]

QUOTE: Originally posted by Stuckarmchairing

I've seen it done, at a local club theres a Cow/calf set that operates on the same address, Im not sure how the owner does it, but when you call the locomotive up (I believe its something like #1076 and #1076b both the cow and the calf react.)

Most people do that with two decoders. Are you sure that is not what he is doing?

[onetrack64]

Yeah, I know I could use a second decoder. But that would be too easy!!! I just picked-up a second Proto 2000 GP7. I don't mind MU-ing them permanently... thats how the railroads ran them years ago. Actually, it would be something like they do now with a mother-slug set-up[;)]

Don

[rexhea]

Don,
The problem I see with doing this, is each motor will have different inherent electrical characteristics that will make one run different than the other. There would also be a difference in the locos themselves such as weight, balance, and gearing. With the use of only one decoder, you would not be able to match the locos by programming.

REX[:)]

[grandeman]

I agree with what others are saying about potential problems. Another you may not have considered is that the second loco would always have to face the same direction as it was wired for, no turning it around unless the wiring was reversed as well. One benefit would be extra electrical pickups, sort of like a powered tender on a steamer. This is an interesting idea. It makes me wonder if manufacturers couldn't put a real MU plug in the locos to accompli***he same thing with fewer decoders.

[grandeman]

Ya know, I wonder if there'd be any market for a dummy with electrical pickups/lights and an MU plug to augment the power supply to powered locos? Maybe an NMRA standard plug so you could mix and match brands. A dummy shell is also a good place for sound.

[nfmisso]

Don,

Go fo it. I believe that the biggest challenges is going to be the wiring bundle between the two units. With no lights, you are looking at four wires, six with just one controlled light.......

You probably should consider some sort of draw bar (dummy couplers glued together maybe) between the two, so that the wiring is not taking the stress.

[roadrat]

If you ran the wires out of the lead loco at about the place of the MU lines and painted them black with just a touch of silver at the center they would look like real MU lines, just a little out of scale.

sounds like a cool project keep us posted[:)]

bill

[onetrack64]

Hi again! I come back and I smell smoke...somebody's thinking again[:)]

I was going to start out with what should be two identical P2K GP7's. That should eliminate alot of problems up front. I wasn't worried about the electric pick-up, if it's good enough to power the decoder normally. My main thought was to use the reserve decoder power to run the second motor. And I was going to run the wires to resemble the prototypes, it just might not be scale size. Now I can use those photos I've taken over the years.

[onetrack64]

PS: I love this "hobby"-in my case it's almost an obsession! It keeps me out of trouble (?) and give me something to do while I'm at the hospital when I'm not assisting in my wife's care. Having a laptop and permission to tap into their network is great.

And I'm glad to have so many responses to my idea. Keep them coming!

Don

[rexhea]

Don,
If your Locos are matched as well as you stated, then go for it. I have two Atlas Gold SD24s that are extremely close to identical and I didn't have to tweak the CVs to MU them. Just make sure your decoder will handle the amps.

REX [:)]

[Anonymous]

I would go for it!! Gee, you could use black small gauge wire and run from one to the other to represent MU lines, and they actually WOULD be.

[Anonymous]

Go for it Don and keep us posted. Maybe I'll then try it in N scale.

[SpaceMouse]

QUOTE: Originally posted by onetrack64

Hi again! I come back and I smell smoke...somebody's thinking again[:)]

I was going to start out with what should be two identical P2K GP7's. That should eliminate alot of problems up front. I wasn't worried about the electric pick-up, if it's good enough to power the decoder normally. My main thought was to use the reserve decoder power to run the second motor. And I was going to run the wires to resemble the prototypes, it just might not be scale size. Now I can use those photos I've taken over the years.

I had P2K F2A/F2B unit. The B unit would lap the A unit every 4th lap on a 4x8 layout.

[cacole]

Something no one has considered in these messages is, you're doubling the current draw on the decoder when you connect it to two locomotives, turning it into a smoke generator if you choose the wrong decoder.

You will need a decoder that can handle double the current load of a single loco, and are thus more than doubling the cost of the decoder.

Just use two separate decoders set on the same address or run them as a consist.

If you still want to try running two locomotives from one decoder, how do you propose to control the lights?

[rexhea]

Don/cacole:
Don, another thing to consider is if you need to break up the MU'd locos, how are you going to use the one without a decoder. Examples of this would be going to the engine house or turntable and the times when you have a short consist with a local run. I believe you would be eliminating your operational flexibility by using only one decoder. Yes, the idea would work electrically with two well matched locos using a properly rated decoder as cacole and I have stated, but do you really want to loose all the capabilities of the second loco.

REX [:)]

[jfugate]

Most HO locos draw about .2 amps, so two locos will draw about .4 amps, which is well within the current limit of most HO decoders (1 amp).

But I would test the locos on pure DC first to make sure they run similar speeds. Put them on the track separated by about about two feet and then run them around at different speeds. They should keep roughly the same distance apart and never meet at any time no matter how fast or slow you run them.

Otherwise, you are better off to spend the extra $20 and get yourself another decoder for the other unit.

[Anonymous]

QUOTE: Originally posted by SpaceMouse

QUOTE: Originally posted by Stuckarmchairing

I've seen it done, at a local club theres a Cow/calf set that operates on the same address, Im not sure how the owner does it, but when you call the locomotive up (I believe its something like #1076 and #1076b both the cow and the calf react.)

Most people do that with two decoders. Are you sure that is not what he is doing?

Whoops, my bad I read the question wrong [xx(]

[onetrack64]

I'm back. jfugate, that's what I figured as far as the current draw. I usually use Digitrax decoders, and many of them are rated at 1.5 amps with a peak of 2 amps. And I'm not worried about loosing operational flexibility... I have plenty of other horses in the stable to run. I wouldn't need the headlights facing each other, I'd just run the connection to the far end of the second unit. That would be good enough for me, I'm certainly no "rivet-counter"
This idea have been bouncing around in my head for a while. I have thought about most of the questions raised. I just wanted to see if anybody else has actually tried to do it. And also to see if there is anything I forgot to factor into the equation.

Who mentioned N-scale...if you can pull that off, you are the Master.[bow]