harddrive motors

[Callipygous]

ive been taking apart old harddrives and now have several of the motors used to spin the disks. id like to play around with them and im curious how to do it without burning them out. they all have three electrical contacts, so i need to know what each of the contacts are, so i know how to wire it, and what voltage i need to use.

 

can anyone help me out?

[Dave]

You're unlikely to burn them out unless you put quite a large voltage across the terminals. I would suggest trying a fairly reasonable voltage (5-12V) and connect them up to two of the terminals until the motor starts to spin. I don't know whether there's any sort of standard when it comes to this though, so probably best for YT or someone similar to answer who probably knows the answer

 

(Moved to Engineering since it seems a more appropriate place than GD).

[Externet]

Hi.

Three terminal hard drive motors are three phase motors. You will not make them spin applying 12V DC to them.

Follow the traces of those three terminals and do a web search for the integrated circuit that connects to. Look for its application notes and then you can saw-off the portion of the board containing the circuit and ancillary components to make it run.

Miguel

[Callipygous]

ok.... i have several of the circuit boards from the back of the harddrives, im sure i can find a way to work with that... maybe.

 

also, in the past, with ones i didnt care about, i have touched it with 9 volts dc and it definately spins. due to the way i set it up i could only touch it for a second, what would happen if i kept contact?

 

actually, that may have been one with 4 contacts... not sure

[Callipygous]

also, im curious what my limitations are going to be...

 

i know they will go plenty fast for my purposes (7200 rpms is more than enough) but im guessing that comes along with being fairly weak. would 4 of these be able to give a RC car any kind of respectable acceleration?

[YT2095]

the ones with the 4 contacts are remarkably similar in operation to Stepper Motors, they have one Common pole and the other 3 are then pulsed in sequence 1 2 3 1 2 3 etc...

each pulse turns the motor a few degrees. so with a simple ripple counter you can drive a small motor, and by adjusting the clock for the ripple counter you can vary the speed to an exceptional degree of accuracy. most of them have a speed sensor local to it and some even built in, this sensor then regulates the clock frequency so that a constant speed is maintained at all times.

 

they won`t work like standard angular motors though, they do need a driver/support circuitry.

 

single chip linear motor drivers are quite cheap and very easy to wire up though

 

btw, they lack sufficient torque to be of any use in RC cars, even 4 of them.

[Dave]

This is why I always suggest other people answer electronics questions

[Externet]

Hi.

Hard drive motors do not have enough torque to use them as propulsion on a RC car. But they could be used for RC airplanes.

The plan to use hard drive motors just because you have them at $0 is not a good decision as they add too much complexity to your project. Their control circuitry is meant to spin them at a steady speed to ensure data stream uniformity which does not go well with other applications.

Miguel

[Callipygous]

Hi.

Hard drive motors do not have enough torque to use them as propulsion on a RC car. But they could be used for RC airplanes.

The plan to use hard drive motors just because you have them at $0 is not a good decision as they add too much complexity to your project. Their control circuitry is meant to spin them at a steady speed to ensure data stream uniformity which does not go well with other applications.

Miguel

 

 

you're underestimating my geekiness.

 

the reason for using these is not just because they are free, but because then i get the satisfaction of having used harddrive motors to make some fun toy. any fun toy. any creation using some other kind of motor would simply not be as cool as if i used harddrive motors.

 

 

also, im confused about the physics behind the torque part of it. if i gear it down enough so it can move the car shouldnt it reach about the same speed as if i used it for an airplane? basically, isnt the motor capable of the same output no matter how its applied, and it just needs to be set up in such a way to take advantage of its strengths?

[YT2095]

if you gear down, you`ll lose any speed advantage you`de gained from using this type of motor in the 1`st place though.

 

lets ignore torque for a second, lets bring it down to a more Fundemental unit of Watts, and RC car motor uses power in the 10`s of watts or more.

A HDD motor wouldn`t even get close to double figures.

 

therein would lie the problem

[insane_alien]

you could shove a blob of blue tac on the axle and start the motor and see how fast it can spin before it gets pulled apart.