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Discussion Starter · #1 ·
Compadres!

Is there some sort of core to magnify an electro magnet that doesn't isn't in itself magnetized?

If I want a solenoid to alternate between two magnets and use an iron core as magnifier, then that core will get drawn towards the magnets when idle, or engaged at low power.

What core could be used to avoid this side effect?

Erik
 

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Rich Dumas
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3,600 Posts
I suppose that there is a reason that you are not using a spring loaded solenoid. In order to enhance the effect of weak magnets I used to use aluminum plates. I had a reference to something that might work better, but I have not been able to find it.
 

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Discussion Starter · #3 ·
Thanks RichD, and you're quite right that there's a reason.


So an aluminium core would actually work? That would be so good that it's almost unbearable. I really got to get that SlotZ project ahead one more step.
 

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rich d, would the ally plates work on an old johnston motor, if so where would they go. top and bottom of the motor or bent round the sides. cheers john.
 

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Rich Dumas
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The aluminum would only tend to concentrate what is already there, I used to do that with magnetic stirring plates in the laboratory. The effect is not huge and may not be great enough to be of any use with either the solenoid or motor application. Did the old Johnston motors have Alnico magnets? If so you might get them zapped, Alnico demagnatizes fairly easily. Some people stack a couple of neodymium magnets on those old motors and have reported an increase in performance.
 

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Eddie Grice
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QUOTE (RichD @ 22 Feb 2012, 15:03) <{POST_SNAPBACK}>Did the old Johnston motors have Alnico magnets?
Think it was the Pittman open frame motors that used Alnico magnets.
Most if not all can motors, such as the Johnston use a magnet produced by a sintering process.

stoner, if you want better magnets in a Johnston just bung in a couple of SCX can magnets

Eddie
 

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QUOTE (RichD @ 23 Feb 2012, 17:37) <{POST_SNAPBACK}>You can also stack neodymium magnets on the outside of can style motors that have weak magnets.
Not as effective as it sound. Due to how the strength will be dispersed over the radii there will be next to nothing left to boost with. The iron cast will add to this too, is my feeling.

Far better to chuck the original magnet and repalce it with a much (much!) smaller neo.
As Im do with my HO cars. Tyco 440 work very well this way and I am even getting the Life-Like working.
Next up is Aurora Magnatraction. Aurora sans MT! And how weird does that sound?


QUOTE (stoner @ 24 Feb 2012, 09:56) <{POST_SNAPBACK}>neodymium magnet have a north and south pole, so does a motor, how do you make sure the poles line up, or doesn,t it matter. john.Check with a compass. It'll disregard the iron cast. The neo will disregard the poles of the ferrite inside and smack onto the same cast regardless of original pole.
 

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Slot King
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Or you could find some of those nice soft cobalt magnets designed for the Johnson can, and fit it with a nice 16D arm.
But then again, it wouldn't be a Johnson anymore would it?
Surely the fun of the Johnson motor is how slow and weedy it is, rather than it's great speed.

Joel
 

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Discussion Starter · #14 ·
We're talking about that blue motor in old Scalextric cars like the Electra, Javelin, Ferrari and Ford, right?
I must ask...
...when was that motor slow?



But then again, if it's the one the likes of Triumph TR7 etc, then a spanking new RX-42B would do wonders, for the straight line speed that is...
 

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Discussion Starter · #16 ·
Thanks gasowder.
So that Johnson is an RX? A Johnson 16D?

What's the blue one then?

The one earlier than that is the remarkably wonderful to drive RX-1, right? The one with only one magnet.
 

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Eddie (Gasowder) is talking about this motor - the Johnson 111 as fitted to 1970s Scalextric cars before they went over to a S-can Mabuchi with quite a large "window".



Soft motors, run bloody hot, smell like an electric motor should do.

The big motor in late 1960s Scalextric cars (Miura, Ford 3 Litre etc.) with the sky blue can (also in pink/cerise) is also a Johnsons motor but a Johnsons 16D. All manner of blueprinting can be done on these and by blueprinting I mean where modern Super 16D bits accidentally get mixed up on the workbench and find their way inside the can...
 

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Discussion Starter · #18 ·
As I thought then. The Blue Thunder (or Cerise Gordon) is the Johnson 16D of fame, glory and speed. Thanks.
 

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Eddie Grice
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I did wonder Mike, knew I had mine off Chas when I returned to slotracing about 1985, 27 awg armature, still got it somewhere but the endbells seen better days

Eddie
 
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