mini electric motor

[john walker 3Participant @johnwalker3]

If anyone is looking for very small electric motors the vibrating tooth-brushes by Wisdom, Oral-B etc contain motors approx. 12mm long x 5mm dia. at 1.5v

just unscrew the end cap and pull out the mechanism.

There is a small out of balance weight on the shaft which I’m sure can be removed.

Wouldn’t like to try changing the brushes though.

[john walker 3Participant @johnwalker3]

[Ian S CParticipant @iansc]

Hi John, I’v got one 8mm x4mm, with a 6mm long shaft, and two othersabuot the same size as yours. These ones came out of cell phones. An idea I had for using them was a site on Google about some one making a radio controled aircraft powered by a cell phone battery. I’v removed the out of balance wgt from one of the larger ones, forgotten how i did it, think there was some thing on the net about how, and I followed that. Ian S C

[Peter G. ShawParticipant @peterg-shaw75338]

Ian,

 

I’m intrigued. What would a cellphone use a motor for? Could it be the vibrating alarm?

 

Regards,

 

Peter

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Peter, yes it is usually for making it vibrate. Just has a lmp of plastic or diecast on the shaft which is sometimes kinda half moon shape.

 

Regards Nick.

[John OlsenParticipant @johnolsen79199]

This always intrigues me, since I am sure that a cheaper vibrator could be made with a metal reed with a small steel weight hung on the end, next to a small coil. Just drive the coil with pulses at the resonant frequency of the reed and it will vibrate like mad, no need for bearings and commutators and the like. The electronics to drive such a thing would be cheaper than a motor these days. Not too mention that in my experience, small motors are not happy with out of balance loads.

 

regards

John

[Tony JeffreeParticipant @tonyjeffree56510]

Posted by John Olsen on 10/02/2011 08:58:21:

This always intrigues me, since I am sure that a cheaper vibrator could be made with a metal reed with a small steel weight hung on the end, next to a small coil. Just drive the coil with pulses at the resonant frequency of the reed and it will vibrate like mad, no need for bearings and commutators and the like. The electronics to drive such a thing would be cheaper than a motor these days. Not too mention that in my experience, small motors are not happy with out of balance loads.

 

regards

John

 

Given the price sensitivity of cellphones, I would be very surprised indeed if they hadn’t figured out what was the most cost-effective solution to the problem (at that time).

 

Regards,

Tony

[Peter G. ShawParticipant @peterg-shaw75338]

Thanks Nick,

 

Peter G. Shaw

[Ian S CParticipant @iansc]

Just been looking at the motors, the shaft is .5mm dia. The weight is crimped on the shaft, on one motor the weight has a slot in which the shaft lies, the edge of which is crimped over the shaft, the other one, the shaft is in a hole, and the crimp is in the form of a center pop on the thin side of the weight. Ian S C

[Billy MillsParticipant @billymills]

Simular motors are used in electric flight, geared down 4:1 or so to drive a small prop. or as the muscle in very small servos.

 

Regards

Alan

[John HaineParticipant @johnhaine32865]

Phones are extremely price sensitive but also extremely power sensitive – anything to reduce current is highly desirable. Motors are much more efficient than oscillating or linear magnetic displacers, and given the enormous volumes of cellphones (1.6 billion last year – I think only electric motors, ironically, are made in larger numbers) it was well worth developing very small motors for the purpose.

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