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Battery powered/Radio controlled locos


StuartM
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While waiting for the Deltang reed switch Rx's i have been thinking about double headiing and there seems to be a basic problem. This lies with the batteries and not the Rx etc.

 

Say you are using a single lipoly cell giving a nominal 3.7 volts. You start at 4.2 volts then the voltage drops as the battery discharges. This means 100% throttle on the Tx delivers less 'volts' to the motor as the battery discharges. This is OK for a single loco but if you have 2 bound to the same TX channel it does not matter if they are the same loco type and manufacturer. If the batteries are at different stages of their discharge cycle they will be delivering different voltages and the locos will run at different speeds!

 

Or is the Rx sophisticated enough to deliver say the equivalent of 3.1 volts at full throttle throughout the cell discharge cycle? In essence giving a flat discharge curve?

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I am planning to control my locos from my PC. That way each will be controlled separately and the power level could be tweaked upwards on a loco that is running slowly.

 

It may also be possible to have some system to monitor motor speed so that could be used by the throttle and not just "power". I suspect it would be difficult to fit speed measurement into an NGauge loco so I may not be the one to experiment with this.

 

It is also possible to measure the battery voltage and maybe that would be a way to build in power/speed compensation.

 

...R

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I am planning to control my locos from my PC. That way each will be controlled separately and the power level could be tweaked upwards on a loco that is running slowly.

 

It may also be possible to have some system to monitor motor speed so that could be used by the throttle and not just "power". I suspect it would be difficult to fit speed measurement into an NGauge loco so I may not be the one to experiment with this.

 

It is also possible to measure the battery voltage and maybe that would be a way to build in power/speed compensation.

 

...R

 

As the Rx is monitoring the battery voltage I suppose it could in theory lower the output 'voltage' by a simple onboard calculation.

 

'Flat' output voltage divided by current input voltage would give a decimal fraction by which to modify the motor output

 

For example new lipo 4.2 volts, required voltage 3.2, modify the throttle output by 0.76

 

part discharged lipo 3.7 volts, required voltage 3.2, modify the throttle output by 0.86.

 

I see one of th new RX chips is now available. I am itching to order some of the reed examples.

Edited by davetheroad
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Robin

 

Thanks for the challenge....

 

But I think it is beyond me at the moment. I'm trying to sort out a stepper drive for the turntable I built in 2010, and finish two locos that I started in 2006 (ok, lived abroad for 3 years, but we've been home nearly 4 and they're still not done) and there are n other unfinished and unloved projects to do... And that's not even considering my competence, or lack thereof!

 

SD

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You can measure the speed of a Permanent magnet DC motor without additional sensors.  You disconnect the power briefly and measure the voltage induced in winding - this is directly proportional to the motor speed.  This is what Back EMF DCC decoders do, try these linksas a starter: http://ww1.microchip.com/downloads/en/devicedoc/41233b.pdf and https://sites.google.com/site/hobbydebraj/home/dc-motor-control-using-back-emf-sen.

 

You can also count commutation ticks, but this is a bit harder to implement reliably. 

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@simond, how are you planning to control the stepper motor? I am using some to (hopefully) make a small metalworking lathe into a combined CNC lathe and a 3D printer. It is easy to control a stepper motor with an Arduino Uno and a Pololu A4988 driver board.

 

I am rotating my train-sized (NGauge) turntables with a servo and using another servo to position it.

 

...R

Edited by Robin2
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Happy, Happy

 

The reed switch receivers are now available!

 

I have ordered 3 plus the Tx22 transmitter.

 

I already have the lipos and charger and have been butchering a Dapol dummy class 86. This will be the freight test bed and there will be a dmu as well plus the little class 08

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@ Robin

 

yes, that's the plan.  I have a Metalsmiths O gauge GWR TT, all finished on top, but not motorised - I'd like to set up something that would allow me to push a button and it aligns with either a preselected track, or the next track - haven't quite sorted that in my mind yet.

 

The other attraction is that Arduinos will drive 6 servo motors - which cost something like half of a Tortoise point motor and also allow for the "prototypical bounce" if used for signals. 

 

So I see the Arduino as a useful bit of kit,. and one that I would like to learn more about

 

And then, as you say, you can convert a lathe or milling mc to NC control...  could add to the modelmaking arsenal too.

 

I'll keep you posted with progress!

 

SD

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  • 3 weeks later...

Check this link out for my first conversion of a Farish class 08 to battery power and radio control.

 

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=17291.0

 

It works really well and i am so impressed that I am going ahead with other locos etc.

 

Nice one

One day ALL model locomotives will be powered by a rechargeable battery and controlled by a radio link

As I said in my original post on this thread, with larger locos the battery's could be made into the shape of the chassis and then there would be no need for a trailing battery/Transmitter/Receiver in a wagon or carriage.

I think the next step you could try, is seeing if you could reduce the battery/Transmitter/Receiver into a shunters truck?

Good effort though, well done and Keep up the good work

Rgds

Stuart

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Check this link out for my first conversion of a Farish class 08 to battery power and radio control.

 

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=17291.0

 

It works really well and i am so impressed that I am going ahead with other locos etc.

 

I like the HST, which really lends its self to this method of traction/control

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  • 3 weeks later...

Hi all,

 

I have read this thread with fascination!  I am part of the 'returning after 30+ years' brigade and am building my first 'proper' layout, which for various reasons will be 00 and DCC - although in the interests of economy and experimentation it will utilise RPI and Sprog 2.

 

BUT...  What I really want to model is 7mm Narrow Gauge - 0n16.5.  My worry was running 0-4-0's and maintaining continuous pick-up.  And justifying a second workstream to The General Manageress.  But building a NG layout using battery/radio control sounds like it could be done on a reasonable budget AND result in smooth operation.

 

For what it's worth, I agree with many of you guys on here - this technology is the future.  Is anybody trying to define standards yet?  Is there any international cooperation?

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Welcome to the future and this thread.

 

For what it's worth, I agree with many of you guys on here - this technology is the future.  Is anybody trying to define standards yet?  Is there any international cooperation?

 

I wish, we can't even get the likes of Bachman, Dapol or Hornby to take an interest let alone reach international agreement

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Check out http://freerails.com/view_forum.php?id=45 this appears to be the most comprehensive discussion area for radio control and battery power. There are several there who model On16.5. At least at that scale you have a good chance of fitting everything in the loco.

 

There is no international agreement and I don't know of anyone thinking of defining standards. From my limited experience it looks as if the nearest to a standard is systems such as those produced by Deltang http://www.deltang.co.uk/

 

which utilise the same technology as model planes, cars and boats using the 2.4Ghz band. These systems use Spectrum DSM2 and DSMX transmitters which makes them very resilient to interference and I suppose is a standard within the radio control hobby.

 

Of course I had to take the hardest path and model in n-gauge where fitting everything in is a challenge, however the 'trains' I have converted run happily on my DC layout without any brown outs or assistance from the hand of god. In fact I only turn the power on so the controllers aux output can power the point motors. What is good about BP/RC is the converted locos will run on 'live' Dc and DCC layouts. This means you can try a conversion or two without re chipping all your motive power.

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There is some activity too on http://ngrm-online.com

 

This is narrow gauge; although mostly 009 there is I think some O-16.5 and other scales.

 

I model mainly 009 and you can see that there but I am putting radio control in a Smallbrook Studio kit at the moment and it seems to fit quite well.

 

As you say, small 0-4-0 locos do not always run reliably and that is why I have tried out radio control and the results are simply stunning!

 

The locos just run when you turn the knob, no tapping the baseboard, no nudging, they just go!

 

Frank

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The locos just run when you turn the knob, no tapping the baseboard, no nudging, they just go!

 

Frank

 

I think people who haven't tried BPR/C will find it hard to understand how much better this is, it immediately feels altogether different - you really do need to experience it. It's probably because the uncertainty about "will it move" is gone.

 

...R

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Having spent several hours reading the threads at freerails.com (thanks for the link, davetheroad), it answered my question re: international cooperation - Brits, Yanks, Germans all contributing there!  It would also seem that DelTang is working collaboratively (and speedily) with model rail customers towards a common set of requirements, and solutions.

 

All of which has led me to taking the plunge!  Yesterday I ordered an 'ALBA' kit from Smallbrook with the appropriate donor loco for conversion to BP/RC.  Unfortunately, despite being the far side of 50, these will have to go to Santa to be delivered on Christmas Day...  Best to humour the other half, I suppose.

 

By the time I get to unwrap these goodies, I will have put together a test track and gathered together all the tools and bits I've been buying for the last couple of years and so will be ready to begin the conversion, which I will cover in a separate thread.

 

In email conversation with Michael from Smallbrook I learned that he is a fan of BP/RC having built and run a 1/32 ng battery powered layout some years ago.  He pointed out that the Smokey Joe chassis used by many of his kits usually have a 3v motor with extra resistors to operate on 12v, so potentially good candidates for battery operation.  He thinks there may be an option to offer a hollow boiler for some kits to create battery space.

 

Andrew

Semi Fast

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Having spent several hours reading the threads at freerails.com (thanks for the link, davetheroad), it answered my question re: international cooperation - Brits, Yanks, Germans all contributing there!  It would also seem that DelTang is working collaboratively (and speedily) with model rail customers towards a common set of requirements, and solutions.

 

All of which has led me to taking the plunge!  Yesterday I ordered an 'ALBA' kit from Smallbrook with the appropriate donor loco for conversion to BP/RC.  Unfortunately, despite being the far side of 50, these will have to go to Santa to be delivered on Christmas Day...  Best to humour the other half, I suppose.

 

By the time I get to unwrap these goodies, I will have put together a test track and gathered together all the tools and bits I've been buying for the last couple of years and so will be ready to begin the conversion, which I will cover in a separate thread.

 

In email conversation with Michael from Smallbrook I learned that he is a fan of BP/RC having built and run a 1/32 ng battery powered layout some years ago.  He pointed out that the Smokey Joe chassis used by many of his kits usually have a 3v motor with extra resistors to operate on 12v, so potentially good candidates for battery operation.  He thinks there may be an option to offer a hollow boiler for some kits to create battery space.

 

Andrew

Semi Fast

Welcome to the cause and good luck with your conversion, be sure to let us know how you get on

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Hi Andrew, and welcome!

 

I am working on a Smallbrook conversion too, a Hero, although I have a different chassis from the Smokey Joe, as I used one I had already. I would be interested to see how you get on with the Smokey Joe.

 

So far things have gone OK. The main point has been the solid casting that is the boiler. This is the obvious place to put the batteries but needs hollowing out. I opted instead to replace it with some brass tube as I had some the right diameter. A hollow boiler option would be very useful.

 

Otherwise it looks to be fairly straightforward.

 

Good luck, and keep us posted.

 

Frank

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I received an email from 'themodelworks' last week saying:

 

 

your 850 Class is almost completed, running under battery power and in the paint shop.  even more important the drive mechanism & battery (360Mah) is fully contained within the frame/boiler, which should give the nay sayers something to think about.

 

post-20667-0-85690900-1387129981_thumb.jpg

 

post-20667-0-14053700-1387130014_thumb.jpg

 

Hopefully I will get it back from Australia sometime in January and will then be able to run it on the trackwork I am slowly building

 

jayell

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