Ok the question was asked of me tonight and I thought I knew the correct answer but wasn't sure.
If your running tow locomotive in a permanent lash up such as a pair of FA/FB or FA/FA units connected by a draw bar is it possible to wire both units using a single decoder? I realize there may be an issue with the directional lighting but that doesn't seem too difficult to figure out. My only concern was would the decoder be able to handle the draw of two motors instead of the normal single one.
If this is possible to do it would not only save you a few bucks on the second decoder but would eliminate the need to consist the locomotives with two addresses etc. A plausible idea or file it as a no go.
If you use 2 decoders, you can speed match and then set them to the same address. This way you are not setting up a consist and only using one address.
In O scale, it is not at all uncommon for one loco to have 2 motors driving different trucks. This is really no different to what you are proposing. Just make sure the current draw is within the decoder capability and it would work.
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A few bucks is about all it will save. Good decoders can be had for around $20. A single decoder would need to be able to handle the current draw of both engines. It would need to be wired between both engines which would require a minimum of two wires jumping between them to connect the motor and decoder. Four wires if the decoder would be powered by their combined track pick up. One or two more for lights. That still would not make them a perfect match because no two motors and mechanisms are exactly the same. (Many are close, though)
Two decoders could have the same address a.k.a.simple consisting. Normal direction of travel can be set in each decoder. Speed tables could be programmed differently to match each other. They could be tested and serviced separately. To me that last one alone is worth $20.
Martin Myers
I have always wondered what happens with the BEMF when using one decoder for two motors, does anyone know?
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Can you? Yes.
Should you? Well, I wouldn't, it's not like you are saving big bucks and flexing wires between units increase failure risk. If you want to control lights then the wire bundle will be significant and visible.
But that's just me. They are your engines.
Dave
Lackawanna Route of the Phoebe Snow
Phoebe VetCan you? Yes. Should you? Well, I wouldn't, it's not like you are saving big bucks and flexing wires between units increase failure risk. If you want to control lights then the wire bundle will be significant and visible. But that's just me. They are your engines.
Actually addressing *only* the lighting aspect and ignoring all of the other (well-founded) issues...
If the locos are to be permanently (or mostly permanently) MU'd then controlling the lights on the second unit shouldn't be a huge issue other than the actual wiring itself. The size of the wires though can be small, particularly if he's using LED-based lighting. With LED's the current draw is trivial so you could easily get away with scale-sized wiring of perhaps 20-22 gauge or thereabouts. You would probably want to do it up so it looked like MU cables, or at least like a brake line hanging below the couplers-- you could wrap the wires in black shrinkwrap and still be in the right ballpark size-wise.
But you most definitely could not (should not) attempt to do that with the motor wires-- they would need to be much larger in order to handle the extra current without burning up. Although you *could* theoretically do the wires in parallel and have several wires that carry each leg of the motor and perhaps make it look like they've been MU'd-- I have my doubts as to whether or not you could do that in such a way as to look even remotely realistic.
John
Yes you can.
I did it once as an experiment a few years ago. I used a Miniatronics 4-conductor wire set. I connected the locos together electrically and used the other two wires for the motor in the trailing unit.
If I recall correctly the decoder was a Digitrax DH123. The lash-up (a pair of Athearn BB F7s) worked okay, no overheating or cut outs from the decoder. Since the pair was an AB set I wasn't concerned with lighting on the B-unit.
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Allan
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Sometimes you can get attractive prices on decoders. For example I've seen TCS T1 decoders for around $16-$18, especailly in multiples. At the Worlds Greatest Hobby train show, TCS has had special show prices of their T4X decoder. The T1 has 2 functions, and the T4 has 4 functions. Both have back EMF. I bought mine to use in Athearn RTR tunnel motors and SD45's. They have built in lighting effects like Mars or Pyle gyralights etc.
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Allegheny2-6-6-6If your running tow locomotive in a permanent lash up such as a pair of FA/FB or FA/FA units connected by a draw bar is it possible to wire both units using a single decoder? I realize there may be an issue with the directional lighting but that doesn't seem too difficult to figure out. My only concern was would the decoder be able to handle the draw of two motors instead of the normal single one.
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Some PCM FA/FB and F3 A/B sets came form the factory as "smart dummy" sets, where the B unit had electrical pickup and a speaker, with a wire harness passed through the end doors to a single LokSound decoder in the A unit. I'm fairly certain they had motoors as well that were controlled by the decoder in the A unit.
I've contemplated building one of these, but haven't tried yet.
Whith Loksound at and QSI $100 each, that's a fairly nice potential savings.
I also have no problems with BEMF decoders fighting each other, and I have several sets of ABA cab units, some with dummy B units, where all the decoders are either ESU orQSI.
I really don't have any grades, thoufg. that may be where the problem comes in.
I am building a 2.2% helix. We will see wha thappens then.