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Jack Benson

DJM on DC

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Hi,

 

Are DJM 4mm products unsuitable for use with DC or are there caveats?

 

Cheers

 

Jack

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The 14xx/58xx they did for Hattons seems to be more problematic on DCC than DC, based on what's appeared on this forum in the past. The DJM locos I have—a Kernow O2 and a 'NQP' 58xx acquired from Dave at a show last year—are both fine on DC. They do have coreless motors so won't run correctly on feedback controllers. That also applies to a number of recent Bachmann models, too.

Edited by D9020 Nimbus
Added 58xx in first sentence.
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As Nimbus has said, some of his models use coreless motors and run like a bag of nails on DC feedback controllers. Pure DC is fine though.

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3 hours ago, D9020 Nimbus said:

The 14xx/58xx they did for Hattons seems to be more problematic on DCC than DC, based on what's appeared on this forum in the past. The DJM locos I have—a Kernow O2 and a 'NQP' 58xx acquired from Dave at a show last year—are both fine on DC. They do have coreless motors so won't run correctly on feedback controllers. That also applies to a number of recent Bachmann models, too.

 

Er...Which Bachmann ? There have been assertions to that effect but AFIK not from Bachmann.

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5 hours ago, Jack Benson said:

Hi,

 

Are DJM 4mm products unsuitable for use with DC or are there caveats?

 

Cheers

 

Jack

 

It's feedback controllers and electronic track cleaners that are the problem. The same applies to Rapido and some others.

 

A normal controller should be fine. But if you have something out of the ark that grandad used in the 1950s then I would recommend buying something a bit more modern anyway.

 

FEEDBACK:  Feedback controllers create a closed loop between the controller and the locomotive which senses the load in the circuit and constantly adjusts the output.  This will maintain the locomotive at an even speed up and down gradients and around curves without altering the regulator of the controller.  Feedback controllers are not suitable for Portescap or other coreless motors or for poor quality mechanisms particularly in ‘N’ and other small gauges

 

 

http://www.gaugemaster.com/glossary.html

 

 

 

Jason

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11 hours ago, Steamport Southport said:

 

It's feedback controllers and electronic track cleaners that are the problem. The same applies to Rapido and some others.

 

A normal controller should be fine. But if you have something out of the ark that grandad used in the 1950s then I would recommend buying something a bit more modern anyway.

 

FEEDBACK:  Feedback controllers create a closed loop between the controller and the locomotive which senses the load in the circuit and constantly adjusts the output.  This will maintain the locomotive at an even speed up and down gradients and around curves without altering the regulator of the controller.  Feedback controllers are not suitable for Portescap or other coreless motors or for poor quality mechanisms particularly in ‘N’ and other small gauges

 

 

http://www.gaugemaster.com/glossary.html

 

 

 

Gaugemaster's statement above is fine in respect of Gaugemaster's Feedback DC controllers - crude, 50hz feedback, designed for thumping old heavy Hornby Double-O motors into life is a bad idea on coreless motors.    But its also wrong in the general case.

 

Appropriately designed feedback controllers are fine, and will work extremely well.  For example, the no-longer available Pentroller DC controller (designed with the Portescap motor/gearbox in mind), and just about every DCC decoder chip on sale (some makers document specific settings for coreless motors). 

 

 

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3 hours ago, Nigelcliffe said:

 

Gaugemaster's statement above is fine in respect of Gaugemaster's Feedback DC controllers - crude, 50hz feedback, designed for thumping old heavy Hornby Double-O motors into life is a bad idea on coreless motors.    But its also wrong in the general case.

 

Appropriately designed feedback controllers are fine, and will work extremely well.  For example, the no-longer available Pentroller DC controller (designed with the Portescap motor/gearbox in mind), and just about every DCC decoder chip on sale (some makers document specific settings for coreless motors). 

 

 

 

That post could cause confusion. Especially in the mind of the average person buying RTR and plug in controllers.

 

 

Do not use feedback controllers with coreless motors. It could fry them. Just read the appropriate threads and dare I say the instructions.

 

If you've got a feedback controller or one over about twenty years old? Do not use with DJM or Rapido models. In the former case you aren't going to get a replacement for your damaged model...

 

 

 

Jason

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20 hours ago, Ian Hargrave said:

 

Er...Which Bachmann ? There have been assertions to that effect but AFIK not from Bachmann.

Several Bachmann models in OO have coreless motors—the new versions of the Ivatt 2-6-2T and the V1/3 to name just two, together with many N gauge steam locos and the 009 Baldwin. There have been several reports on this forum and elsewhere of problems using such models with some feedback controllers at least.

 

AFAIK Bachmann don't as yet have an official position on this, though there have been several reports on this forum of issues with models—especially the 009 Baldwin—being allegedly blamed by Bachmann on the use of feedback controllers.

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4 minutes ago, D9020 Nimbus said:

Several Bachmann models in OO have coreless motors—the new versions of the Ivatt 2-6-2T and the V1/3 to name just two, together with many N gauge steam locos and the 009 Baldwin. There have been several reports on this forum and elsewhere of problems using such models with some feedback controllers at least.

 

AFAIK Bachmann don't as yet have an official position on this, though there have been several reports on this forum of issues with models—especially the 009 Baldwin—being allegedly blamed by Bachmann on the use of feedback controllers.

 

It has long been known (early 90s or before) that coreless motors and feedback controllers do not work together. Usually results in a loud buzzing noise from the locomotive, followed by smoke.

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4 minutes ago, Joseph_Pestell said:

It has long been known (early 90s or before) that coreless motors and feedback controllers do not work together. Usually results in a loud buzzing noise from the locomotive, followed by smoke.

 

I ran a Portercap powered 07 shunter for many years on Melbridge Dock using Gaugemaster feedback controllers. It made a whining noise, but never faltered over many hours of exhibition operation. 

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11 minutes ago, Phil Parker said:

 

I ran a Portercap powered 07 shunter for many years on Melbridge Dock using Gaugemaster feedback controllers. It made a whining noise, but never faltered over many hours of exhibition operation. 

 

I'm not that familiar with Gaugemaster equipment: More of a KPC man. The KPC Feedback controllers had a switch to turn off the feedback facility.

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I would also guess the Portescap motors were much better quality and durable than the ones used on DJM models.

 

Aren't these small coreless motors designed for use in things like laptops?

 

 

 

Jason

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On 04/07/2019 at 13:19, Steamport Southport said:

 

That post could cause confusion. Especially in the mind of the average person buying RTR and plug in controllers.

 

 

Do not use feedback controllers with coreless motors. It could fry them. Just read the appropriate threads and dare I say the instructions.

 

If you've got a feedback controller or one over about twenty years old? Do not use with DJM or Rapido models. In the former case you aren't going to get a replacement for your damaged model...

 

 

 

Jason

 

Hmm, so I shouldn't use a Pentroller feedback controller designed for coreless motors on coreless motors. As the lucky owner of a couple of these (lucky as you cannot buy them anymore) I think I'll just carry on.

 

I would have thought the advice should be - feedback or not - check if your controller supports coreless motors. If it dosent say so, then it probably doesn't.

 

I won't be using my H&M Duettes  on coreless motors, even though they have no feedback...

 

Chris

Edited by Chris Higgs
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It's up to you.

 

Just don't expect a replacement if your model goes up in flames as it clearly states in the instructions not suitable for feedback controllers.

 

But people telling others it's fine because their controller works can be a bit naughty when they plug in their feedback controller that isn't designed for coreless motors and ruin their model. Especially when both the model manufacturers and the most popular controller manufacturer are telling people not to use them.

 

 

 

Jason

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As an end user, I own several DJM 18" Austerity models, without any problem. My controllers are Gaugemester, and an old H&M Duette.

ian.

 

(A DC Luddite).

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Early DCC decoders with feedback shouldn't be used with coreless motors. Later ones using so-called "silent" back-EMF should be fine. They are much higher frequency; one of the reasons they're silent. The lower frequency ones like most feedback controllers make any motor grumble a bit, and will shake a coreless motor to bits. If there's such a thing as a high-frequency feedback controller it should be OK.  I think the instructions on the Gaugemaster site as to which of their controllers you can use with coreless motors are pretty accurate, as you'd expect.

 

The KPC hand-held controller with a button to "turn-off" feedback didn't actually turn it off, just reduced it to minimum level. Whether that's good enough is for you to judge.

 

Currently I've been trying out a number of coreless motors from various sources, all of them with a basic Gaugemaster Combi controller. They work fine.

 

 

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The main problem with coreless motors is that because they are an efficient design that has low current draw they tend to over-react to feedback, and this usually results in what could be termed ‘jittery’ running at times. This can often be exacerbated by poor current collection, dirty track/wheels, which magnifies the effect.

 

As this is quite separate from the issue of pwm frequency, even when high frequency feedback is used it is usually the case that reduced feedback rates are needed to assist them in not suffering over-reaction. This is why many DCC decoders have alternate cv settings for them.

 

Sadly, most DC feedback controllers don’t have adjustable feedback rates, which I believe was a feature of the Pentroller mentioned previously. Interestingly, a lot of the more efficient conventional (iron rotor) motors made today often suffer in much the same way as coreless. 

 

Izzy

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16 hours ago, Izzy said:

...

Sadly, most DC feedback controllers don’t have adjustable feedback rates, which I believe was a feature of the Pentroller mentioned previously. Interestingly, a lot of the more efficient conventional (iron rotor) motors made today often suffer in much the same way as coreless. 

 

Izzy

 

Indeed. I've used Mashima motors quite a lot, and found they made a nasty grinding sound when used with feedback controllers. Don't know whether it actually damaged them but it didn't sound good. So I stopped using feedback controllers. Mashimas are pretty smooth anyway, and so long as there are no gremlins in the chassis I find feedback isn't really needed.

 

Nigel

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The Pentroller is ideal for coreless motors and the PICtroller - its modern descendent with automatic motor type sensing  - works OK in the large panel mounted version.  Stewart Hine, who made the Pentroller, was never worried about HF track cleaning devices and coreless motors.  We used them on Copenhagen Fields for many years with no motor problems whatsoever. 

 

Tim

Edited by CF MRC
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OK, thanks.

 

The general rule for coreless and better, modern motors is to use a handheld controller that is unavailable. 

 

Hmmm.......this leaves our group wondering what to do next, presumably there is a handheld controller that does not have feedback or PWM but is currently available? Does anyone offer an available handheld DC controller that meets with anyone's approval?

 

 We just bought the Gaugemaster HH and an AGW PE100 handheld which work fine with our fairly modern Bachmann locos (after this episode, I doubt if we will even consider any DJM items)  We tried Gaugemaster's advice service but they seemed intent on steering towards the Combi and refused to answer any question about the Australian as it was intended only for the overseas market. Possibly their W Handheld might be suitable but we became wary of their responses and decided to ask on RMweb.

 

We rejected the Morley devices, as being rather strange - base unit and a handheld - and cannot find if KPC offer a suitable handheld???

 

Thanks, until we can find more suitable answers to our needs we will continue to use our HH and AGW controllers and merely restrict our motive power although we do have a Mashima driven loco 'in build' 

 

Cheers

 

JB

 

 

 

 

 

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The Gaugemaster model W handheld is fine for coreless motors, that is what I use as well as KPC switchable controllers. Not sure what is going on with KPC? I bought mine a long time ago when they had a shop in Gravesend.

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Thanks for the advice,

 

A Gaugemaster W duly popped up and was snapped up. Just waiting for a new DIN plug to arrive, then I will report back with its performance set against their HH and the AGW.

 

JB

 

 

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