Radio Control

[Frank]

I have just put together an 009 Peco GVT tram loco kit and fitted it with radio control.

The body is on a Kato tram chassis instead of the bulky mechanism it was designed for, and this gives enough room for a single cell LiPo battery (nominal voltage 3.7V) on top of the chassis.  The radio is a 2.4 GHz system from David Tang based on the new systems for electric aircraft models but adapted to "land based" models, and the controller looks like a normal railway model controller with a knob for speed and a switch for direction.

It runs very smoothly and the battery should last at least 3 hours - I have not managed to run it down yet!

Here is a video of the loco running round a train on my "developing" layout (really just track so far):

http://youtu.be/EcuNpjhJ7JQ


and here is a closer look at the loco uncoupling:


http://youtu.be/0gAhnJqODNI


It runs very smoothly.   It's not awfully fast (the video shows it at full speed) but it's fast enough to by prototypical I think.   It has really good slow speed control, like DCC, and of course it does not hesitate at points nor refuse to start without a nudge or a prod.  I think this is the most impressive part, you turn the knob on the controller and it just starts off! 

In the uncoupling video for instance it's very easy to position the train over the uncoupler (I'm using Greenwich couplings with under track magnets).


Frank

[tedp]

That is most impressive - excellent control, too. The first appearance of a new way of control in 009? If it catches on, this is a true revolution.

[Frank]

Thanks Ted.

I put this together to see if it would work and I think the answer is yes, it does work.   Control is very good and it completely does away with the "nudge" when the loco does not start or gets stuck on points which is so annoying and quite a problem for 4 wheel locos particularly as they have fewer wheels in contact with the track.

Batteries have just reached the point where they are small enough to be fitted into a biggish 009 loco.  The issue it not endurance (I think this loco will run for at least 3 hours on the battery in it).   The issue is speed, as higher speed needs more cells which need more space, but modern motors will run OK on low voltage.

Frank

[Graeme Dunbar]

Fascinating and impressively smooth.  Where did you get the radio control gear? (I assume it is not David Tang of fashion shop and restaurant fame  :laugh: )

Edit - Found it! -
http://www.deltang.co.uk/

[Frank]

Graeme,

The radio control gear is described here:

http://www.deltang.co.uk/

as you have found.

Scroll down to Surface Receivers - surface as opposed to airborne.

The website does not sell them but there is a link to stockists; I got mine from Micron Radio Control.

The receiver is the low power low voltage one that comes with flying leads for easy connection:
Rx41d-v5-W

There is also a larger one that will handle higher voltages and currents.

There are different versions of the receiver that are set up as two channel - one for speed and one for direction -or one channel - speed and direction combined, centre off.   I have the two channel version as above.

The control unit AKA transmitter is the TX21 which you can buy as a kit or ready built - I built mine and it was fine.

Frank

[Hugh Norwood]

I was impressed with this at the AGM. I think that with a bit of ingenuity, it could be made to take its power from the tracks - with some sort of "keep-alive" circuit to cope with dirt etc.

[Frank]

Thanks Hugh,

I think you are right that it could be made to work on track power.   Using a battery means finding space for the battery, using track power means finding space for a capacitor which should be easier.

You would have to have track power on all the time though.   The current system can be used on a DC or DCC layout.   Using track power you would probably end up only being able to use it on DCC layouts.

Frank

[rod335]

Just a thought, I really like the idea of a loco HAVING to go on shed every now and then (to recharge the battery), say a short length of track DC powered in the shed, the rest of the track being dead. Any takers anyone? Or is there an inherent flaw to this idea?

Rod

[Graeme Dunbar]

There is a bit of a discussion of this on NGRM-online.

As I understand it, it depends very much on the batteries. I had not appreciated how "picky" the new Lithium Polymer (LiPo) batteries are when it comes to charging and charging in a siding, at a station etc would not seem practical.

However, older rechargable batteries such as NiCds are a lot more forgiving, if less "efficient". I believe that the Faller cars in the magnificent Miniatur Wunderland in Hamburg have "wing mirror" charging contacts that charge the cars as they are parked, so it is possible.

This suggests a novel twist on running a layout for battery technologies that permit flexible charging: how about a charging point at a coaling/refueling station - or more pragmatically (as you suggest) trickle charging in the engine shed, station or siding?

[Frank]

I think the main difficulty with rechaging LiPos from the track is that they do need very careful control of the charging process.   This means I think that you would have to supply track power to the loco and mount the charging circuit in the loco itself.  You could not just connect the charger to the track as it would not then be able to sense the battery voltage reliably enough.

So you would have to find room in the loco for the charger as well as the battery.

I think that LiPo batteries will last a couple of hours or more between charges, more with intermittent running, and are cheap enough (a few pounds each) to have two and swap them over when needed, so I think that recharging them isn't really an issue.

Frank

[MickT]

I only managed a very brief glimpse of your loco running without track on the glass top of the  Society display case at Rainford but have to say I was very impressed indeed with what I did see!

I suppose the next challenge will be to fit a Robert Thompson (RT Models) Portram powered Lister or even a Portram powered Roco "gravity" skip wagon with the radio control stuff!

For sale - Triang variable resistance power controller - it appears to be obsolete....................

Mick

[Graeme Dunbar]

It depends on the design of the model but the swapping the battery aspect makes me a bit uneasy as it means frequent handling and possible dismantling of the locomotive. It would be less invasive if there was a charging socket under the loco (as in Faller road vehicles) and the loco charged off the track but with the battery in situ.

It would be interesting to investigate what the most effective combination of battery, charging method and running scheme is.

At one end of the spectrum we have the traditional continuous power to the rails and at the other there is full battery operation with separate charging. In between there is the very short term "stay alive" capacitor used on some DCC systems to deal with intermittent electrical contact, but as of yet I'm not aware of medium term storage, e.g.

1. continuous power
2. stay-alive (say from a fraction of a second to a few seconds reserve)
3. station to station
4. one journey
5. part or all of a "shift"
6. one day operation/overnight recharge

With batteries, size and shape is very important as is energy density, but only in terms of miliWatt-hours per cubic metre and not per kilogram. In fact, to an extent, the heavier the battery the better, so what is best for phones and other mobile devices may not necessarily be best for model railway use.

The use of radio control certainly opens up all sorts of possibilities....  :)

[Hugh Norwood]

The web site mentioned above for these devices shows a transmitter for 3 locos.... (!)

[Frank]

As you say, Hugh, there is a version of the transmitter that will control three locos at once with three speed control knobs.   It works out at less than the price of two individual transmitters so is pretty cost effective.

As Grahame says, swapping batteries is an issue but I have found that the battery lasts for a whole operating session so you don't need to handle it any more frequently than when getting it out and putting it away again.

You could have a charging socket say under the loco instead of having to take it out to charge but being able to swap batteries easily means you can swap a charged one for a used one.

But it's horses for courses.   It's probably cheaper than DCC for a few locos whilst offering at least equivalent control, and can be used on a DC layout along with the DC locos, but does not yet offer sound etc. like DCC nor can you control lots of locos from the one controller.

And it would currently be difficult to convert really small locos and bigger, older chassis which have high current consumption, because of the difficulty of fitting a suitable battery in.

Frank

[Isle of Stoner]

I had a good play with Frank's loco at Rainford and was incredibly impressed with the controllability and how having an onboard power source improved this. I get pretty good running but this was better.

One tricky thing that occured to me is that I have a stupidly large number of locos so would it be necessary to have a controller per loco or could some sort of switch be incorporated? Different channels for different locos, otherwise it would be only any good for 'one engine in steam'  running.

Definitely a technology which would make trackwork able to be much more realistic NG style. Rust and lumps and bumps which would stall a conventional DC or DCC loco would be fine with self powered RC.

Game on. I'm getting RC twitches... maybe a bespoke layout with loads of mucky, jubilee track...


John W