Feedback controller for shunting?

[TT-Pete]

Perhaps I should have phrased the question as "What controller is best for a shunting layout?" As I understand it a feedback controller senses the load on the loco and so maintains a constant speed, which sounds like it would be ideal for slow-speed shunting, no? I know they are not recommended for coreless motors (but I don't know why)  or  for older vintage or N scale locos, but as I already have this one to hand

 

 

 

I am wondering if it might be suitable...?

 

[Joseph_Pestell]

13 minutes ago, TT-Pete said:

 I know they are not recommended for coreless motors (but I don't know why) 

 

 

 

I am wondering if it might be suitable...?

 

 

Hi Pete,

 

You would soon know why coreless motors are not recommended with feedback controllers. A loud buzzing sound followed rapidly by a smell of burning.

 

That is a fairly ancient looking Gaugemaster that you have there but will probably be fine.

 

KPC used to make some very good units, with optional feedback on a slide switch.

 

But my favourite was the little handheld units by ECM. They were laid out very well for ergonomics with everything accessible with one hand, even for someone as ham-fisted as me.

[d00m]

ECM rambler minor... Still using the two I purchased in 1982 - Almost impossible to find now....

 

[TT-Pete]

14 hours ago, Joseph_Pestell said:

You would soon know why coreless motors are not recommended with feedback controllers. A loud buzzing sound followed rapidly by a smell of burning.

 

That is a fairly ancient looking Gaugemaster that you have there but will probably be fine.

 

Ah, that sounds like a high-risk scenario! How does one tell if a motor is coreless or not before putting the loco on the layout and potentially frying it? Do the advantages of using a feedback controller outweigh the risk?

 

I think Dad bought it around 1980 so it  has been lying around for decades, would have been nice to use it, but if it's the wrong tool for the job....

 

[Colin_McLeod]

12 hours ago, d00m said:

ECM rambler minor... Still using the two I purchased in 1982 - Almost impossible to find now....

 

 

There is a panel mounted version on Ebay at present.

 

https://www.ebay.co.uk/itm/334020933527

[d00m]

They are ok, but not quite as good as the handheld for shunting.

(I have some of these and some of the version with the adjustable pwm on two different layouts - I use the rambler for the yard/depot and the panel mounted to control the main).

I have been looking for other solutions and there is a thread on here (electrics, non dcc) discussing a very nice (and cheap) option in 'best all round dc controller'.  Motor  governor - ZK-MG

Edited June 7, 2021 by d00m

[AndyID]

17 hours ago, TT-Pete said:

 

Ah, that sounds like a high-risk scenario! How does one tell if a motor is coreless or not before putting the loco on the layout and potentially frying it? Do the advantages of using a feedback controller outweigh the risk?

 

 

Without actually taking it to bits, if you are able to remove the motor when you spin it by hand it won't tend to "cog" at all (like a cored motor), and it will take very little effort to make it spin.

 

DCC systems can use PWM with coreless motors but they have to operate at high frequencies that are not really compatible with non-DCC controllers that have to send the PWM power down the track.

 

Despite some of the wavy-arm nonsense posted about DCC and coreless motors the main reason coreless motors overheat on PWM is their lack of inertia due to their low rotating mass. As soon as the power is cut they slow down and it's the continuous deceleration and acceleration with PWM that makes them overheat and vibrate. (At higher frequencies they have less time to slow down.) One possible solution is to stick a flywheel on the motor but clearly that's not possible in a lot of locos.

[PatB]

If you're feeling a little creative, a simple Darlington pair transistor controller is dead easy and cheap to construct and can work very well. I have a minor hobby of breadboarding Roger Amos' designs (with adaptations to suit components that are locally available and/or didn't go out of production 30 years ago), and have found them all to be pretty good with the limited variety of motors I have available for testing. Basically, X04s, the cans used in the Chinese Smokey Joe, and the open can thingy in recent Hornby 0-6-0s. Oh, and, in substantially beefed up form, the ancient and current hungry wound field pancake in vintage US made Marx 0 gauge stuff, but that's probably a bit niche to be relevant.

 

And, yes, I'm well aware that real electronics experts consider the Darlington pair to be ridiculously outdated. Quite possibly true, but I like simple and cheap, and it works for me.

[Michael Edge]

I have coreless motors (mostly Portescaps) working quite happily with Gaugemaster and AMR feedback controllers - no buzzing or overheating at all. The feedback doesn't make any difference to shunting performance in my experience.

[Captain Kernow]

2 hours ago, Michael Edge said:

I have coreless motors (mostly Portescaps) working quite happily with Gaugemaster and AMR feedback controllers - no buzzing or overheating at all. The feedback doesn't make any difference to shunting performance in my experience.

I have been using AMR slow-speed hand-held controllers for years, including with a few Portescap-fitted locos with no problems at all, long before I was aware that there was a kind of gentle feed-back happening with the AMR units.

 

I recently acquired a new Gaugemaster feed-back hand-held, in order to have a back-up available, but I think I'd hesitate before using this with any coreless motor, particularly in view of the dire warnings given by the Gaugemaster chap, when I rang up to order it.

 

[Captain Kernow]

I was also in contact with Jim Read recently, who kindly sent me the specs for one of his controllers described here - 

Whilst there is no way that I would be able to make head or tail of how to build one of these, I did send the info over to a friend in our club, who has now built one for me to trial. Generally it's very good, although the start up is very slightly too 'sudden' for my liking, requiring extremely careful operation of the controller, so my friend thinks he can adjust the start up range in due course. It's possible that this issue is not a result of Jim's design, of course, but due to the fact that my friend had to change one or two of the components specified, due to supply issues.

 

 

 

[Stevebr]

Hi Jim,

 

I would really appreciate the pdf. 
 

Steve

 

[DCB]

Duplicate.

 

Edited November 18, 2021 by DCB

[DCB]

On 08/06/2021 at 10:03, Captain Kernow said:

I was also in contact with Jim Read recently, who kindly sent me the specs for one of his controllers described here - 

Generally it's very good, although the start up is very slightly too 'sudden' for my liking, requiring extremely careful operation of the controller, 

 

That is the main problem with shunting controllers and RTR locos, getting a smooth transition from stopped to moving.  This whether the controllers have a reversing switch and 270 degree rotation like the gaugemaster, or 120 degrees off 120 degrees like a Morley or old H &M.  I use H&M and Morley  and fit the largest control knob I can find. On the Morley I have a home made Hand held where the knob is wider than the body giving really easy one handed control.  But it's judgement.

 

If you do settle on the controller in Jim Read's video why not have a secondary resistance controller and reversing switch in series, any old thing.   Set the speed on the main control and fine tune with the resistance. I have used a Triang Minic reversing hand throttle for the purpose. or just use an on off reverse switch. I quite often shunt the loft layout just using the reversing switch when the speed has been set and the abrupt stars are no less realistic than the momentary overspeed most people get when trying to do a smooth start with fancy controllers.