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johnarcher

Old controller with coreless motors.

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Thanks for that miaco, that's a good find.

I would appreciate similar informative articles.

 

 

Kev.

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I think one thing that has confused some people is that they think a coreless motor is brushless.

All DC motors must have brushes. AC motors usually don't but can have.

Even what is called a "Brushless" DC motor (BLDC) isn't a DC motor at all as it is a type of AC motor with a driver board to convert the DC into a form of AC (pulses, whatever)

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6 hours ago, maico said:

 

You could do but aliaexpress is full of fake and used stuff. These are fakes for example...

 

I was somewhat surprised by the £3.74 price - I remember Maxons being somewhat more pricey when I used to use them!

 

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2 hours ago, AndyID said:

 

and even then if you run the poor thing into the buffers and it stalls it's likely to overheat. Ideally you want a controller with sensitive over-current protection.

I'm old fashioned. All my portescaps have a 250ma (I think) fuse.

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27 minutes ago, melmerby said:

I think one thing that has confused some people is that they think a coreless motor is brushless.

All DC motors must have brushes. AC motors usually don't but can have.

Even what is called a "Brushless" DC motor (BLDC) isn't a DC motor at all as it is a type of AC motor with a driver board to convert the DC into a form of AC (pulses, whatever)

Coreless motors don't have brushes. They use gold wipers.

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21 minutes ago, Denbridge said:

Coreless motors don't have brushes. They use gold wipers.

What is the difference?

The one I posted pictures of doesn't have gold anything.

 

  • Agree 1

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41 minutes ago, sharris said:

 

I was somewhat surprised by the £3.74 price - I remember Maxons being somewhat more pricey when I used to use them!

 

I suspect they are a batch of surplus as the quantity is somewhat limited compared to most "Made in China" stuff, legit or otherwise.

There are plenty more in the £30+ bracket.

Edited by melmerby

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30 minutes ago, Denbridge said:

I'm old fashioned. All my portescaps have a 250ma (I think) fuse.

 

That's a very good idea.

 

Do you unscrew the dome to expose the fuse holder ;)

 

 

  • Funny 1

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14 hours ago, Denbridge said:

Coreless motors don't have brushes. They use gold wipers.

 

You mean they have gold brushes. Brushes do not need to be carbon.

 

Which reminds me, someone, in one of the scale societies I think, investigated coreless failures and it was the flimsy brushes that were the failure point, not the armature windings.

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On 12/10/2019 at 03:09, Crosland said:

 

You mean they have gold brushes. Brushes do not need to be carbon.

 

Which reminds me, someone, in one of the scale societies I think, investigated coreless failures and it was the flimsy brushes that were the failure point, not the armature windings.

 

Ah, but all that glitters is not gold. A few microns of gold-plating isn't going to survive for very long.

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On 12/10/2019 at 11:09, Crosland said:

 

You mean they have gold brushes. Brushes do not need to be carbon.

 

 

Gold doesn't seem to me a good material for motor brushes as it is easily worn down.

We had a lot of trouble where I worked with gold contacts wearing through on such things as switch wipers.

It's great for things that are only occasionally separated like plug-in board conectors or multiway sockets.

Edited by melmerby

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More than a decade ago Marklin introduced what they call Softdrive Sine AC motor. No commutators or brushes to wear out. The 12 pole magnets are skewed to reduce cogging at low speed.

 

 

Edited by maico

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2 hours ago, maico said:

More than a decade ago Marklin introduced what they call Softdrive Sine AC motor. No commutators or brushes to wear out. The 12 pole magnets are skewed to reduce cogging at low speed.

 

 

But no good  for a DC supply!

 

Another brushless design is this multipole motor which is driven by a 3 phase signal from a control IC:

capstan_motor.jpg.55f5edf8f83d0ab827afca4cd032b2b1.jpg

 

With the rotor on:

1864269390_motor2.jpg.f044f63ea8958d9bd7503e3f6f10c5bd.jpg

 

The magnet(s) are a ceramic ring. Speed is monitored by a hall device.

It is very smooth running.

It runs off 12v DC and I'm trying to find a model railway use for it!

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