# LGB DUO SWITCHING LOCO



## Madman (Jan 5, 2008)

I have one of LGB's Duo switching locos. Those of you not familiar with these unique locos will find this interesting. The loco has automatic couplers, hook and loop, that uncouple when a certain amount of power is applied to the track. Turning the throttle up more moves the loco away from the uncoupled cars. This is all done via analog power. No digital or DCC or similar high tech stuff. 

My question is this; would this locomotive be able to operate on battery power?


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## TonyWalsham (Jan 2, 2008)

If you only wanted to control the speed and direction the answer is YES.

If you also wanted to operate the uncoupling feature it would probably be possible if the on board ESC had a linear output. 
However, most ESC's do not have a linear output. They typically all use PWM which cannot be adequately smoothed out by simply using capacitance. 
So the answer is really I doubt it.


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## Madman (Jan 5, 2008)

I kind of figured as much Tony. I have just started converting to battery power. Although my track is still powered, as I am not planning on converting all of my equipment. I must say, however, that so far I am very pleased with operation using battery and R/C.


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## Dan Pierce (Jan 2, 2008)

Would a bi-polar cap across the motor filter out most of the PWM to give the appearance of DC power? Something like a 15UF non-polarized cap? 

I do this to reduce the ping on my Aristocraft reversing unit and it works well.


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## TonyWalsham (Jan 2, 2008)

If you put too much capacitance across a pwm output the FET(s) will overheat, plus the smoothness of the drive is compromised. Even a value of 1µf will make the motor start up much more sudden. .1µf is about as much as you can use.


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## Jerry McColgan (Feb 8, 2008)

Posted By Madman on 29 Apr 2011 07:29 PM 
This is all done via analog power. No digital or DCC or similar high tech stuff. 

My question is this; would this locomotive be able to operate on battery power? 


Hi Dan,

Those little LGB Switchers are among my very favorite locos. I really wish LGB had put that system into a full size switcher.

As tiny as they are, where would you find room to put a battery and receiver?

You mentioned no digital or DCC which suggests to me that you have the 21900 (red) rather than the 23900 (blue) which came with a decoder installed.

I know virtually nothing about converting locos to battery power and even less about wireless DCC operations but, with this in mind, perhaps this may be of assistance in that it shows how to convert a 2190(0) to DCC. All I know is that I happened to have the document but I know nothing about how to make the conversion (and I don't speak or read German).

http://1stclass.mylargescale.com/je...to-DCC.doc

Perhaps this document can help you get to where you are trying to go. It might enable someone to figure out how to make a 21900 work with a regular RC system. I don't know.

I hope you are able to make it work because that would make a really neat addition to a battery powered layout.

Jerry


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## Madman (Jan 5, 2008)

Since I have started conversion to battery power, I have decided on trailing cars for the battery and receiver. This allows me to run any loco with on battery power. It also saves some money.


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## TonyWalsham (Jan 2, 2008)

Dan, 
What you might be able to get away with is isolating the motor/lights from the uncoupling device and powering only them with the motor driver output. 
It should then be possible to use the pure DC battery voltage to operate the uncoupling device separately with a function output on the ESC. You may need a suitable small relay if the current consumption of the uncoupler coil is high.


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## Jerry McColgan (Feb 8, 2008)

Perhaps you could do something like this:











I put the car in the middle to have a sound unit and still have both front and rear coupling/uncoupling. The other reason was that the little 0-4-0's don't have a lot of traction and this doubled the traction. Since I run on track power this combination also gives me a total of 12 track contacts which is great for running through multiple turnouts.

A middle car that looked like a calf unit would have been better but I never found anything that I thought looked right.

Jerry


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## Madman (Jan 5, 2008)

HMMM, some food for thought. Both sound like good ideas.


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## Jerry McColgan (Feb 8, 2008)

Hi Dan,

If you do decide to do something like my photo, all that I had to do was to remove two screws to open the hood and unplug the one jack (disconnecting power to the rear couplers).


























Since the 21900's are purely DC voltage controlled (including the lights and uncoupling) I wonder if you could not get by with some sort of POT (circular rheostat) connected to a servo such as used in radio controlled aircraft. In effect it could work like the elevator of an aircraft - up would advance the voltage forward and down would advance the voltage in reverse. With the servo moved far enough the uncoupling would occur.

If the radio control did nothing other than rotate a rheostat, pure battery DC voltage could be used and the round two pin connectors at the back of the 21900's could be used with no modification to the locos (assuming there was neither a short nor power on or between the rails).

I am talking about something I have never tried to do and I do not know what radio control servos & rheostats are available to make it happen but this just seems to me to be what might be a super simple solution for what you are trying to do. I have bought very inexpensive two channel radio control toy trains and aircraft that just might have had the components to make it work with a servo on the right frequency. I am not suggesting anything for or against any RC brands - just an idea of what seems to me might work for you.

It seems to me that what you are trying to do is essentially the very same thing that the old Bachmann battery powered 10 Wheelers and New Bright locos did (but I never took one apart to see how the motor voltage was being controlled). Also, the voltage of the Bachmann and New Bright locos would have been too low to make the uncouplers work.

Then again it is always easy to come up with ideas when someone else has to figure out the details of how to make it work.

Good luck,

Jerry


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## Jerry McColgan (Feb 8, 2008)

This is the kind of slug/calf I was trying to come up with:











And this is the sort of pulling power a pair of 21900's have:













Jerry


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## Madman (Jan 5, 2008)

Interesting Jerry. I am operating with G Scale Graphics R/C system. It uses PWM for the output to the motor. I hope that is correct Del. So that system wouldn't work. Somewhere, I believe it was on Youtube, someone rigged up a servo operated coupler. They had it on an LGB loco. I would imagine it would work on any hook and loop coupler on any car. I am using one of these,

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWAX%3AIT, 

to operate my Hot Metal dump car as seen here, 



With some tinkering, I might be able to get one to operate a coupler. I'm not ready to tear aprt my Duo switcher yet.


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## Jerry McColgan (Feb 8, 2008)

I think it was Knut who had previously mentioned (possibly on the LGB Family Forum) a remote controlled hook & loop uncoupling system that (if I am not mistaken) was being offered for sale in Europe. I don't recall the details but I was looking for a way to put the DUO system into a full size switcher.

Years ago I broke the uncoupler on one of my DUO switchers so I started to take it apart to attempt to fix it myself. I quickly realized I was in over my head and put it back together and shipped it to LGBOA where it was quickly fixed and returned. You are probably more mechanically competent than I am but these are some of the few locos that I will not attempt to work on myself - especially now that the availability of replacement parts may be doubtful.

I hope you are eventually successful. In my opinion the DUO switchers represent some of the best of LGB's engineering skills.

Possibly Klaus who is now at http://www.lgbtrainsforever.com/ or Axel at Train-Li-USA might be able to help. Then again you probably already thought about contacting them.

BTW I love your Hot Metal dump car. I think this hobby really needs more action type rolling stock.

Jerry


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