Another DCC Application.

I tend to double motor locos where possible or as with HST's provide two powered traction units, or use twin locos.
Q 1 When using a single locomotive with two motors is it best to employ one high output decoder and reverse the wiring to one motor OR use two normal decoder units and program one motor to run in reverse?
Q2 In the HST case ( and as in Q1 ) can both motors be allocated the same running number but be programmed differently ( ie fwd or rev ) Q3 In the double loco case I would assume the same routine as for the HST except both locos would obey the same ahead or astern command.
Being a devoted DC man my initial forray will be using the Bachmann EZ which I have already.
The problem of employing my return loop with incorporated double slip using double locos and HST's (the length problem) will obviously come up before too long.
All advice is welcome.
Peter A
Montarlot

peter abraham wrote:
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Hi Peter, To be perfectly honest, your best bet is to use two decoders, one for each motor. That way, each decoder can be tweaked to match the characteristics of each motor - eg. starting voltage, etc. You can 'consist' the two decoders, in the same way as if they were two different locomotives. Each decoder can have the direction set using CV 29.
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Slight problem - I dont think the Bachmann controller can do consisting, and it can only address 9 decoders.
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Many DCC manufacturers have a reversing loop module in their product range. The unit takes a feed from the command station and feeds the return loop. This needs to be isolated from the rest of the layout - the isolating section needs to be longer than your longest train if using a power car at each end - and this will allow the train to run around the reverse loop without stopping, and without causing any shorts.
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peter abraham wrote:
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No experience of which is best but if you used two identical motor bogies, for instance, then there's no need for one to run in reverse.
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You can either use the same address or give each decoder/motor its own address and then combine them in a "consist". Any loco or motor in a consist can be programmed to run in reverse. The main limitation is that consist addresses can only be short (2 digit) addresses.
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Does this support consisting in any form?
Andrew

On 20 Apr 2006 12:10:24 -0700, snipped-for-privacy@sheerstock.fsnet.co.uk wrote:
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I have understood that each motor has an ahead or astern which is determined by program selection. If I fit two motors into one chassis then for the same electrical configuration and programming surely they would arrive in opposition - unlike the DC situation - or have I mis-interpreted the DCC methodolgy?
If the EZ can control 9 decoders can I assume that two identically programmed decoders will obey a single command? This would lead to 9 pairs being available provided the motors & gearing were identical and I presume that the 10th position is that of DC?
Regards Peter A

peter abraham wrote:
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It depends how you wire the motors so make sure the motors are wired so that forward and reverse directions are the same.
Chris

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If you do tackel it this way you will require a means of programing each decoder seperately from the other. Which is similar to the problem faced when using sound only decoders. In theory It can be done. You will need those tiny two pin micro connectors and a lot of patience to set it up properly. You also have very limited programming functions with the EZ-Command unit. Your best bet is to use one decoder for both motors. With an HTS you not looking at shunting speeds ?. You will have the obvious problem of motor inbalance, decoder size and capacity.You might want to establish the stall amps to determine the size of decoder required. Perhaps a third method might be even better, look for an alternative motor or better drive system one which is strong enough and offer the control you need.
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wrote:
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I can see where you are all coming from. At the moment I have repair/testing track in my workshop cuddy and I can operate powered bogies using the dummy pick-up bogies in tandem without chassis or bodyshells. It had occurred to me that one could do the same thing to program decoders. I had supposed that the decoded DC would of course work exactly as direct DC so that using one chip would give an output which would cause both motors to run in the same sense.
My reasons for double up motors ( plus double weighting ) is to operate 12 carriage trains up 1:40 and around 2M diam curves. With the HST twin power car + extra weights I cannot manage more than 7 - mainly due to the "pushing" car causing over-runs on the couplings, they being standard h-t type. This problem will only be cured by rebuilding all the couplings or sticking to 5 cars. A good example are the Cl 37's which do not easily modify - there is stacks of motor power but poor adhesion and even with extra weights are not effective and yet the 47's and 25's work like trojans! The only solo performer is the old Cl 52 "Western" which does very well whilst the 58 gets sand kicked in its face by the others! Oh, the ancient Hymek goes like a rocket!
Peter A

peter abraham wrote:
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The problem is that the motors and mechanisms are cheap mass produced units and you cannot rely on them being matched well enough to guarantee that both motors will perform the same, especially if one mechanism is stiffer. A good run in on DC, etc., will help and you may be lucky.
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Decoders with Back EMF feedback should help to some extent in stopping the pushing car from running away. You will still need to tune each one using the speed table to get a close match.
MBQ

peter abraham wrote:
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One solution that no one else has mentioned - wire the dual motors in series. Unless you really want the way out speed, like perhaps for the HST you will be amazed at the controlability of the locos & the loads they will now pull. Since you have included both weights traction is not a problem either, if in doubt add more weight.
Kevin Martin

peter abraham wrote:
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Another solution is to remotor the HST with the innards of a Bachmann 25.... 8 wheel drive and pickup. Also plenty of room for a decoder. (You will need a function only decoder for the dummy power car) The chassis needs cutting and extending, as well as one of the drive shafts, but with a little ingenuity, blood, sweat, tears and swearing, it can be made to fit. However, gone is the 125mph top speed (probably a good thing on a 28' long end to end......) To prevent coupling problems, I've fitted my HST with Keen systems close couplers.
Cheers, Mick

newbryford wrote:
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There was an article in last months British Railway Modelling showing how to do this with pictures for each step.
Chris

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You might want to look at getting yourself a SPROG from Andrew Crossland and then using Decoder Pro from JMRI to do the programming. http://www.sprog-dcc.co.uk / http://jmri.sourceforge.net/DecoderPro /

peter abraham wrote:
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One decoder, if it fits. Two decoders will have to be "consisted", that is, the engine will have to be treated as _two_ engines operating as a multiple unit.
Why reverse the wiring to one motor? The two motors run correctly on DC, don't they?
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Yes, this is called "consisting". You need a DCC system that has this capability, though. It's not a standard feature (IMO it should be.) (Several locos running as a multiple unit is a "consist" over here.)
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See above.
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Bachmann does not support consisting.
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There are automatic reverse loop modules available for DCC.
Also signal controllers, turnout controllers, interlocking systems, etc etc etc. And software that lets you interface your PC with the layout so you can play central traffic controller, if you want. But someone else will be driving the engines, then. :-)

On Fri, 21 Apr 2006 19:32:07 -0400, Wolf Kirchmeir
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I can see the idea of a consist ( loco wise) but I rather assumed it was for addressing two different decoders (with differing addresses) as a temporary single unit. Of course a simple controller like an EZ cannot do this but I am talking of two decoders carrying the same address - what prevents them from both obeying the same command? In the case of an HST / Eurostar etc the train is a fixed composition and excepting failures which require substitutions would always remain in the same configuration.
Before my neurons get too het up - I suddenly found myself worrying about how to identify the "Ahead or Astern" end of such a train or indeed locomotive (DE) as my eyesight is not up to rivet counting any more. It would mean false starts without such a device. I appreciate that steam and US DE models do not pose these problems but UK and CE EL and DE do - at least they do to me!
I do appreciate also that to confine my initial efforts to only 9 operating channels will require isolating bays for other similar addressed locos but then ,joy of joy it is after all a dc system which can accomodate that until I can find a spare IBM 380 to run it all for me . After all, I have spent the last 40 years talking to computers which never replied or made the tea or swept up or gave me anything but trouble ( how very like teenage children they are).

On Sat, 22 Apr 2006 04:51:33 +0200, peter abraham
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Correct.
Nothing, they will both obey the same commands.
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Most (but not all) UK DE locos have a big fan on the roof, that is a good clue and is usually treated as the front end.
For symnetrical trains such as the HST your best bet is to fit directional lighting so that the headlamps come on at the front, in DCC they do this whilst stationary so you can check you have the right direction.
Keith

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Thank you so much Keith - just what I needed. I had overlooked the fan and of course the lamps or headboards will indicate before movement power is applied! here we go then.
Thanks again.
Peter A Montarlot