Re: Small D.C. motor with tacho source


"Dave Boland" <NODARNSPAMdboland9@xxxxxxxxxxx> wrote in message
news:SzUxf.99484$ME5.17180@xxxxxxxxxxxxxxxxxxxxxxx
> I'm doing some software that will measure speed of rotation and
> direction (quadrature). Early hardware not selected, and of course not
> available yet. So does anyone know where I can find an inexpensive d.c.
> motor that has a tacho with signals for speed and quadrature? I've
> looked at Radio Shack, Edmund's, and two robotic web sites so far.
> Spec's:
>
> Speed: Don't care
> Torque: Don't care
> Size: Don't care
> Shaft size: Don't care as long as it will easily connect to tacho
> Voltage: 0 to 5 if possible
> Current: Low current so can run on D cells
> Cost: Very low since this is a throw-away part.
>
> I can't think of anything else to specify. The motor will be driven
> using PWM most likely, but a buffered DAC can also be used.
>
> Thanks for any help.
>
> Dave,
New, no.
However second hand, possibly. In the UK, Distel, has some motors like
this at times, and similar suppliers in other countries may be able to
help. However Distel's prices on these, have shot up recently, since they
are fashionable for 'robotics'. Have you considered the 'silly' solution,
of taking RC servos apart?. Remove the electronics, potentiometer, and end
stops, and you have a lovely cheap geared motor, designed to give good
torque off 5v. You can also add the tacho pickup, where the potentiometer
normally sits. Some of the Chinese units, sold for real 'bargain' models,
are unbelievably cheap,and plenty of people have gone this route:
http://www.andrew-w.co.uk/?c=4&p=7

Best Wishes


.

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