Driving a HDD motor

[nefelodamon]

After a little search I have found this small circuit that the author says it can  drive a Hard Disk Drive Motor. Can anyone verify this please?
The site is: http://grant.solarbotics.net/Circuits.htm
ant the circuit

Thanks

 

[audioguru2]

The BUZ11 is an ordinary Mosfet that needs 10V on its gate to fully turn on. Maybe a few in a bucket-full might turn on enough with only 4.8V. The 74AC14 has an output voltage only 4.8V.

You wouldn't need to test a bunch of Mosfets for a low threshold voltage if you use Mosfets designed for logic-level input voltage.

 

[nefelodamon]

You mean simply that that the motor will not run at full speed or that will not work at all.
If its the first case right its ok with me because I don't want full speed.
Anyway can you recoment any replacements for the BUZ11? 

 

[audioguru2]

Look in a catalog of millions of Mosfets to find some that work with only 4.8V on their gate. Most online catalogs like at Digikey allow you to select spec's.

 

[fever16]

i also would like to know the buz11 replacement.
iam unable to find one in my area.
and how much voltage can i feed to the HDD motor(min and max)

 

[audioguru2]

A hard drive operates from a 12V supply. The motor might survive 15V for short periods.
I don't have a list of Mosfet substitutions. I just select a Mosfet that is available from a list of them that have the spec's I need.

 

[MP1]

After a little search I have found this small circuit that the author says it can drive a Hard Disk Drive Motor. Can anyone verify this please?
The site is: http://grant.solarbotics.net/Circuits.htm

The author has been using this circuit in excess of 2 years in robots he builds. I see no reason to rumor that it does not work.

MP

 

[ante1]

The author has been using this circuit in excess of 2 years in robots he builds. I see no reason to rumor that it does not work.

MP

The author refers to this circuit as “very crude” which probably means that he is well aware of the fact that it can be significantly improved!

 

[Ashtead]

This looks like it would run a little 3-phase motor at variable speed, continually. Such motors are used in hard disks to turn the platters, it is basically a small AC motor meant to run continually, and not really a stepper motor. Like other AC motors, it may likely have a lower frequency limit below which it will not be able to start or remain turning, and when stopped, there is little or no holding torque. 

The commonly seen stepper motors that are used for finely positioning things, have 2 or 4 coils that are driven with quadrature signals (90 degrees out of phase). However, hooking three of the 4 coils in such a stepper-motor might make it run, though somewhat unhappily here...

Also, there is the matter of the transistor threshold voltages that Audioguru mentions. Using a CMOS 4584 at 12V instead of the 74AC14 might work better. with the transistors shown.

Ashtead

 

[MP1]

Sure, I agree this is a simple setup and that there are much more advanced circuits out there. OP stated that the author said it would work with a HDD motor and wanted to know if it was so. I am agreeing that there should be no problem in doing this. Author is clear on his site as to what motor this is for. Also, author has been using this design in his simple robot circuits for better than two years. Sounds to me like it is a bench tested design. Thus my statement, Why rumor that it will not work...  I see a lot of over-thinking functional designs on this site anymore..


MP

 

[audioguru2]

The low output voltage of the logic IC doesn't match the high gate threshold voltage of the Mosfet. Some might work. Some won't work. It is a poor selection of parts.

 

[nefelodamon]

I'm sorry that I have not reply earlyer but I was busy with my work.

I have problems in making the cirquit work.
I 'm testing the circuit in bredboard but it does behave like it should be.
I hear a sound like the motor is spining but in fact is sticked in one position. If I try to rotate it, it moves a little but after a while it stops again.
The measured voltage on mosfets is variable from 0-5V.
I have even try to power the motor with 12V but the result is the same.
By adjusting the 10k pot the "spining sound" changes frequency and I thing the torque of the motor to the oposite direction. Somewhere in the midle I get a smal kick of the motor of trying to get move but it freezes again.

The 4 pins on the back of the HDD are been tried with all the posible position combinations of power and 3 mosfets with the above results in only 2 combinations.

I'm not sure what I'm doing wrong here.

Thanks for the help and your interest!