Coreless motors - what RTR has them?

[Rhydgaled]

On 28/01/2021 at 09:26, mikesndbs said:

What controller do you have?

I have a few kicking around, most of them from train sets. Given that I don't have my layout set up in a fixed location at the moment I use whichever controller is easiest to hand whenever I want to run something. As a result about half the time I use one speed dial on my HM2000 (have no need of the other at the moment) and the other half I use a Hornby R.965. This webpage lists both as feedback models.

 

On 28/01/2021 at 09:57, Legend said:

I would have thought the Model Rail 16xx is more likely to be Coreless . Isn't it made by Rapido for Model Rail ?  Its not on my target list so genuinely don't know . Dibber25 maybe able to help .

Yes, it is made by Rapido, but the specification page in Model Rail lists the motor as  "Five-pole" while the J70 is listed as "Coreless" so I assumed the 16xx would be ok. That said, I think I did read somewhere that a motor can be both five-pole and coreless so I'll ask on the 16xx topic to make sure.

 

On 28/01/2021 at 09:57, Legend said:

I think there is a need for clear labelling  where locos may not suit everyones control set up . I am aware I am a bit of a luddite , but then my set up works well on my existing 100+ collection , I'm not really impressed by being forced to change my set up just to run a few new locos .  But its not just me , feedback controllers are fairly widespread . I think the main Hornby HM2000 is feedback . Probably bought by people who are completely unaware of terms like feedback or coreless. So if locos are being made that aren't compatible with these there should really be a big notice saying so , like you get for DCC fitted , ready etc .  

I agree, if there's a compatibility issue between different products one might use together it needs to be made obvious. I too dislike the idea of having to change my controllers because RTR producers have started using motors that are only compatible with a subset of controllers.

 

21 hours ago, PMP said:

The OO 64xx is not fitted with a coreless motor.

https://albionyard.net/2015/04/02/pannier-capers-the-64xx/

Thanks; I'll have to keep an eye out for Bachmann releasing a second batch.

[melmerby]

5 hours ago, Rhydgaled said:

 

Yes, it is made by Rapido, but the specification page in Model Rail lists the motor as  "Five-pole" while the J70 is listed as "Coreless" so I assumed the 16xx would be ok. That said, I think I did read somewhere that a motor can be both five-pole and coreless so I'll ask on the 16xx topic to make sure.

 

3pole, 5 pole, 7pole etc is the number of poles not a motor type description and can apply to all sorts of designs

 

5 hours ago, Rhydgaled said:

I agree, if there's a compatibility issue between different products one might use together it needs to be made obvious. I too dislike the idea of having to change my controllers because RTR producers have started using motors that are only compatible with a subset of controllers.

 

Hardly a subset, I would suggest rather that those using controllers that aren't compatible are the subset ones

 

There can't be many (any?) modern controllers that cannot be used with coreless.

[2750Papyrus]

Surprisingly many if you care to look, starting with Gaugemaster. 

 

I would have thought it would serve everybody's interests if products unsuitable for a particular type of supply/control were clearly advertised, marked and reviewed accordingly.

[melmerby]

3 hours ago, 2750Papyrus said:

Surprisingly many if you care to look, starting with Gaugemaster. 

 

I would have thought it would serve everybody's interests if products unsuitable for a particular type of supply/control were clearly advertised, marked and reviewed accordingly.

Most Gaugemaster seem to be compatible and have this in the instructions:

"This unit is suitable for use with all types of motors, including Portescap, and High Frequency Track Maintainers."*

 

However I found that the GMC-HH  isn't compatible due to it's feedback

Edited January 29, 2021 by melmerby

[Rhydgaled]

18 hours ago, melmerby said:

3pole, 5 pole, 7pole etc is the number of poles not a motor type description and can apply to all sorts of designs

 

Hardly a subset, I would suggest rather that those using controllers that aren't compatible are the subset ones

 

There can't be many (any?) modern controllers that cannot be used with coreless.

It's still a subset of controllers regardless of whether it is a majority or a minority. If I understand correctly, controllers (the superset) can be divided into feedback and non-feedback, and the feedback ones can be further subdivided into high and low frequency. Low-frequency feedback controllers may make up only a small proportion of controllers, but they are still controllers.

 

Given that Hornby is a major player in the model railway industry and (as far as I'm aware) both my Hornby controller models are feedback (and one of them was bundled with every Hornby train set for a fair period of time) I'd imagine they are quite common.

Edited January 30, 2021 by Rhydgaled

[mikesndbs]

Some clarity on which controllers can and 'should not be used' with coreless designs.

 

Any controller that outputs full wave rectification variable DC voltage will be safe for coreless use.

So an example would be the H&M Safety Minor set to full wave not half.

You would still hear some buzz on starting and it is possible the motor will jump into life but it will not be damaged.

 

So any electronic controller that also uses full wave rectification (100Hz) will be OK, so this includers Gaugemaster types W,D, Combi and so on. The Morley controllers are very safe for use.

 

Older pulse width modulated control designs (including feedback) that use half wave rectification (50Hz) will cause excessive vibration and heat build up that will kill a coreless motor fairly quickly.

Newer designs such as the KPC voltage limited minimal feedback full wave designs (100Hz) will just about be OK for end to end layouts and occasional use.

The well known Hornby HM2000 which uses PWM at 100Hz is not suitable for coreless motors.

And nor are any of the train set controllers, especially that god awful silver and black thing.

 

Hope this helps.

Edited January 30, 2021 by mikesndbs

[Legend]

18 hours ago, melmerby said:

3pole, 5 pole, 7pole etc is the number of poles not a motor type description and can apply to all sorts of designs

 

Hardly a subset, I would suggest rather that those using controllers that aren't compatible are the subset ones

 

There can't be many (any?) modern controllers that cannot be used with coreless.

Like  the main Hornby controller for the last few years , the HM2000 , still listed in current catalogue as R8012 ? It’s not listed as a feedback controller , but I believe it is . Not sure about the other Hornby controllers .  
 

Now I don’t know if this combination of controller and loco will work or not .  But the instructions say don’t use feedback controllers . I can’t see anywhere in Hornby catalogue that says HM2000 is feedback, but I believe it has been confirmed here that it is . The catalogue refers to “compensation to regularise speed under varying conditions of load” without specifically saying feedback . 
 

But my point is , isn’t it entirely possible someone with an HM2000 Hornby trainset fancies some Bachmann locos , say the 1P and doesn’t know they are not compatible .  We have enjoyed a great deal of compatibility in OO model railways for a long time . It appears this may no longer be the case , but it’s not obvious . 

Edited January 30, 2021 by Legend

[melmerby]

5 hours ago, mikesndbs said:

And nor are any of the train set controllers, especially that god awful silver and black thing.

 

Hope this helps.

Are you saying that "god awful silver and black thing" (R8250), the mainstay of many a train set is actually a feedback controller?

I'm amazed, I thought it was just a bridge rectifier - resistance controller.

[mikesndbs]

2 hours ago, melmerby said:

Are you saying that "god awful silver and black thing" (R8250), the mainstay of many a train set is actually a feedback controller?

I'm amazed, I thought it was just a bridge rectifier - resistance controller.

 

Hi there, it's not a feedback controller no, more importantly it is a PWM pulse width modulated type controller and a very crude one at that.

The supplied power supply is 19 volts DC meaning the pulses of power will also have a potential of 19 volts.

It's what makes normal motors runs as if there was sand in them.

 

Feedback is not the issue, its the PWM frequency and maximum voltage that causes heat build up in coreless motors which they are unable to dissipate.

 

High frequency PWM and feedback control together with a limited maximum voltage is perfectly fine.

 

 

[Legend]

28 minutes ago, mikesndbs said:

 

 

Feedback is not the issue, its the PWM frequency and maximum voltage that causes heat build up in coreless motors which they are unable to dissipate.

 

High frequency PWM and feedback control together with a limited maximum voltage is perfectly fine.

 

 

But Bachmann instructions on the 94XX and probably others say do not use feedback controller. So you will invalidate warranty. 

 

To me there should be some clear labelling . In catalogue and on box it should say “this is a feedback controller not suitable for use with all models” and on models with coreless motors “Coreless motor, not suitable with feedback controllers” 

[mikesndbs]

11 minutes ago, Legend said:

But Bachmann instructions on the 94XX and probably others say do not use feedback controller. So you will invalidate warranty. 

 

To me there should be some clear labelling . In catalogue and on box it should say “this is a feedback controller not suitable for use with all models” and on models with coreless motors “Coreless motor, not suitable with feedback controllers” 

 

LOL just shows they have deployed something they don't understand! I presume it comes DCC fitted etc?

DCC I understand uses feedback control, but at a very high frequency something like 20Khz.

 

[Steamport Southport]

32 minutes ago, mikesndbs said:

 

LOL just shows they have deployed something they don't understand! I presume it comes DCC fitted etc?

DCC I understand uses feedback control, but at a very high frequency something like 20Khz.

 

 

They do understand. They aren't DCC fitted unless you buy them DCC fitted.

 

It's people still spreading fake news and rumours that don't understand.

 

The Hornby HM controller isn't feedback and neither are train set controllers issued in recent years.

 

 

This isn't feedback.

 

https://www.kernowmodelrailcentre.com/p/15322/R8012-Hornby-HM2000-Controller

 

Gaugemaster has discontinued most of their feedback controllers apart from a couple.

 

This is the Bachmann train set controller. Not feedback.

 

https://www.kernowmodelrailcentre.com/p/13379/36-565-Bachmann-Power-Controller-and-Transformer

 

 

If you've got an old train set or feedback controller sling it in the bin and buy a new one.

 

It really beggars belief that people are spending £200 on a model and trying to run them on grandad's old controller from 1950 that was found in the attic.

 

 

 

Jason

Edited January 30, 2021 by Steamport Southport

[mikesndbs]

3 minutes ago, Steamport Southport said:

 

They do understand. They aren't DCC fitted unless you buy them DCC fitted.

 

It's people still spreading fake news and rumours that don't understand.

 

The Hornby HM controller isn't feedback and neither are train set controllers issued in recent years.

 

 

This isn't feedback.

 

https://www.kernowmodelrailcentre.com/p/15322/R8012-Hornby-HM2000-Controller

 

Gaugemaster has discontinued most of their feedback controllers apart from a couple.

 

 

 

If you've got an old train set or feedback controller sling it in the bin and buy a new one.

 

It really beggars belief that people are spending £200 on a model and trying to run them on grandad's old controller from 1950 that was found in the attic.

 

 

 

Jason

 

Jason with respect, you are inadvertently causing confusion.

 

It is not the feedback function that is the problem it is the low frequency < 100Hz  pulsed output that is the issue as it causes heat to build up that the coreless motor can not dissipate.

Sadly the HM2000 is a feedback type but again that's not the issue.

Have a read of this excellent page to understand more about the various controllers out there.

https://www.scottpages.net/ReviewOfControllers.html

 

But along the lines of what you have said a Gaugemaster or Morley controller will be fine.

 

[melmerby]

1 hour ago, mikesndbs said:

 

Hi there, it's not a feedback controller no, more importantly it is a PWM pulse width modulated type controller and a very crude one at that.

The supplied power supply is 19 volts DC meaning the pulses of power will also have a potential of 19 volts.

It's what makes normal motors runs as if there was sand in them.

 

Feedback is not the issue, its the PWM frequency and maximum voltage that causes heat build up in coreless motors which they are unable to dissipate.

 

High frequency PWM and feedback control together with a limited maximum voltage is perfectly fine.

 

 

I don't understand.

Why use PWM in a very basic controller and without any feedback?

There is absolutely no point in doing that.*

 

The whole point of using PWM is that you can increase the duty cycle as the load increases to maintain speed, the feedback from the motor between pulses determining the duty cycle.

This is what stymies coreless motors, at low frequencies the feedback is less than that with an iron cored motor and the controller over compensates delivering more power to the motor than necessary and possibly causing overheating.

At high frequencies (say 10kHz and above) there is less of a problem so coreless motors are OK.

 

*A bridge rectifier and a variable resistance works just fine and is cheaper and more robust.

More than adequate as "the trainset" controller.

 

 

 

[Legend]

2 hours ago, Steamport Southport said:

 

They do understand. They aren't DCC fitted unless you buy them DCC fitted.

 

It's people still spreading fake news and rumours that don't understand.

 

The Hornby HM controller isn't feedback and neither are train set controllers issued in recent years.

 

 

This isn't feedback.

 

https://www.kernowmodelrailcentre.com/p/15322/R8012-Hornby-HM2000-Controller

 

Gaugemaster has discontinued most of their feedback controllers apart from a couple.

 

This is the Bachmann train set controller. Not feedback.

 

https://www.kernowmodelrailcentre.com/p/13379/36-565-Bachmann-Power-Controller-and-Transformer

 

 

If you've got an old train set or feedback controller sling it in the bin and buy a new one.

 

It really beggars belief that people are spending £200 on a model and trying to run them on grandad's old controller from 1950 that was found in the attic.

 

 

 

Jason

 But the article that Mike had just posted shows that it is a “thrystor-feedback”  controller .  Actually it also shows that their old R965 is also a feedback controller .  So not fake news at all . 

[Ben Alder]

As my knowledge of such things is somewhat limited, could anyone advise what type of output does the H&M 3000 issue, and the Orbit range from the 1980's.

 

[mikesndbs]

4 minutes ago, Ben Alder said:

As my knowledge of such things is somewhat limited, could anyone advise what type of output does the H&M 3000 issue, and the Orbit range from the 1980's.

 

 

OH wow you have one of those, me too, I knew one of the chaps behind them. Lovely controllers. They are OK but 'may' be a little buzzy sounding on coreless. A small value non polarized electrolytic capacitor placed across the DC controlled output will solve that for coreless without spoiling the controllability of normal motors. Look for something like 47uF at 35 volts.

[Ben Alder]

Thanks - are you referring to the Orbit? Leon Jacobs was behind that IIR, and there is a capacitor fitted across the output that he recommended, that was well before coreless.It is a lovely controller . I resurrected my 3000 after trying a Morley Vector, which worked well but I found better slow speed control with the venerable H&M. 

 

[mikesndbs]

6 hours ago, Ben Alder said:

Thanks - are you referring to the Orbit? Leon Jacobs was behind that IIR, and there is a capacitor fitted across the output that he recommended, that was well before coreless.It is a lovely controller . I resurrected my 3000 after trying a Morley Vector, which worked well but I found better slow speed control with the venerable H&M. 

 

 

A chap called Tony Martin was my contact, yellow fronted controller with a relay delay fitted so everything was charged up etc. Ref the Vector, yes the non crawler type need a small modification to get really good slow speed control. I'll send you a link if interested? 

[NIK]

On 30/01/2021 at 20:51, melmerby said:

I don't understand.

Why use PWM in a very basic controller and without any feedback?

There is absolutely no point in doing that.*

 

The whole point of using PWM is that you can increase the duty cycle as the load increases to maintain speed, the feedback from the motor between pulses determining the duty cycle.

This is what stymies coreless motors, at low frequencies the feedback is less than that with an iron cored motor and the controller over compensates delivering more power to the motor than necessary and possibly causing overheating.

At high frequencies (say 10kHz and above) there is less of a problem so coreless motors are OK.

 

*A bridge rectifier and a variable resistance works just fine and is cheaper and more robust.

More than adequate as "the trainset" controller.

 

 

 

Hi,

 

PWM allows you to use a smaller heatsink on the output semiconductor and possibly a smaller and less expensive output semiconductor.

Also PWM is thought to diminish stiction in the loco allowing better slow running.

It was a popular thing in model railway controllers in the 1970's but then expensive coreless motors came more widely used and things got a bit complicated.

 

If when you said feedback you meant Back EMF feedback being the factor that causes controllers to increase the mark-space ratio of the PWM thus damaging coreless motors I'm not sure that is the main factor.

It is the duration of the mark in the mark space ratio that is the main factor in overheating coreless motors. The higher the frequency the shorter the mark - the on time. When the on time is short enough the lower inductance of the coreless motor is just enough to limit the current (the current doesn't reach damaging levels before the off pulse arrives).

In fact most DCC mobile decoders allow the back EMF feedback to be turned off and I haven't seen a warning about doing that in any manuals. Also back EMF feedback is usually turned off at high DCC speed steps by the decoder. NCE decoders didn't or don't have Back EMF feedback.

 

Regards

 

Nick

Edited January 31, 2021 by NIK

[Ben Alder]

14 hours ago, mikesndbs said:

"Ref the Vector, yes the non crawler type need a small modification to get really good slow speed control. I'll send you a link if interested? "

 

Thanks, the Morley I tested was the Crawler and I was more than pleased with the results but the retro appeal of the 3000 was too much! I sold the Morley on to someone who had admired my older controller and he is delighted with it.

[mikesndbs]

30 minutes ago, Ben Alder said:

 

Thanks, the Morley I tested was the Crawler and I was more than pleased with the results but the retro appeal of the 3000 was too much! I sold the Morley on to someone who had admired my older controller and he is delighted with it.

OK cool, did you ever look inside?

[Izzy]

I believe the problems with coreless motors on DC PWM feedback controllers are two separate issues that are often seen as being the same.

 

One is the low frequency PWM which causes motor heating since the coreless don’t have the iron core mass to absorb it, while it’s the BEMF which is the source of ‘jittery’ running because the coreless often over-reacts to it being more efficient. As has been said with DCC decoders the PWM is higher while with many the BEMF can either be adjusted to suit each particular motor or turned off completely. 
 

With coreless being made en-mass these days as a more efficient/less power hungry design I expect to see most models eventually using them. 

[Ben Alder]

21 minutes ago, mikesndbs said:

OK cool, did you ever look inside

 

No, resisted that temptation...

[mikesndbs]

16 minutes ago, Ben Alder said:

 

No, resisted that temptation...

OK lol keen to find out