hello all,
i have a stepper motor salvaged from old hard disk drive.i want to use this motor in some applications like propeller clock,LED pov etc.for which the motor shld be running contineously.while googling i found below ckt.
http://grant.solarbotics.net/Circuits.htm
http://grant.solarbotics.net/images/...river_ACTU.gif

i have some doubts in the circuit.
the ckt maker said that means every time i have to start the motor slowly at low RPM?
and what shld be the value of "BUZ11 N-CH FET"
what max voltage i can feed to this ckt?

 

Your hard disk uses a stepper motor right?

Therefore it must have a stepper motor driver. I would start by Googling for the chip part numbers near the stepper motor on your hard disk and build a driver from them.

As far as your questions regarding this circuit.

Yes, you do, but it depends on how slowly, you might be able to replace the 10k pot with a 100uF capacitor and 10k resistor in series, the capacitor charging slope will gradually increase the duty cycle untill the motor is 95% on.

Well the author states they've never tested it above 5V, but look at the datasheets of the componants for a clue; these can be found using Google.

well if you need to ask this then you really need to learn more, try Googling for "BUZ11 datasheet" and use a MOSFET with a similar specification.

My final question is do you actually know how this circuit works?

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sorry i shld have red wikipedia about stepper motor first.
now i have some idea abt them.
and abt getting controller from hard disk itself i'll try that.

 

Are you sure it's a stepper?, is it from a really, really old hard disk - 5 or 10 megabytes only?, and pre-286 computers? (and certainly NOT IDE) - anything remotely 'recent' won't use a stepper motor.

I've used stepper motors from old 5-1/4 inch floppy drives, they work quite nicely and are easy to use.

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why motor from HDD is they are quite at high RPM.is it possible with floppy motors.and what ckt did u used to run that 5-1/4 floppy motor..

 

The stepper is for moving the heads, not for spinning the disk - the stepper just requires four drive transistors and the correct sequence, but it's too slow for a propeller clock.

If you're looking at the spin motors?, then they are usually DC brushless designs - and a LOT more complicated to drive without the IC that's designed for it.

All you really need for a propeller clock is a standard DC motor.

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Do you think it's possible to tap into the motor-drive IC outputs to determine the approximate position? With some trial and error, you could program a microcontroller to sense the position based on the outputs of the motor-driver, and create some nifty projects like the LED hard drive clock I've seen going around, but without using a hall-effect or optical sensor.

Any ideas?

 

HDDs don't use steppers for the R/W-heads - far too slow. They have a very strong permanent magnet and a coil being deflected (mounted to the R/W head on a swivel) without any gear in between.

Better to use 3 1/2 or 5 1/4" floppy R/W-motors which are used together with a precision worm gear.

Make small generators easily, too.

Hans

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I know, that's why I specified steppers from a 5.25 inch floppy drive.

Nice strong magnets in duff HDD's though!

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Drill a hole and fix a wire to it. Then stick it up your fridge. Makes moving easier.

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Proper Planning Prevents Piss Poor Performance

 

A friend at work took some to the pub and did tricks with them - they work really well even through a thick table!

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i know that on an older hard drive the motor would spin up once i touched the first few pins on the ide port but it would run for a period of time and stop. if you had a 555 opening and closing the circuit on the pins it could keep it running.