need HD spindle motor driver

[Jim]

I have a number of small spindle motors salvaged from old hard drives that
have only 3 connections. As far as I can tell using my VOM, the 3 coils do
NOT have a common ground connection......or at least I can't find one.

Can someone describe how the 3 coils of this type of (brushless) motor are
driven to make the motor run? I am familiar with HD motors having 4
connections, and there are a number of handy DIP IC's to run this type of
spindle motor, but is there an equivalent IC for use with these 3 coil HD
motors?

Thanks
Jim

 

[Sjouke Burry]

Jim wrote:

I have a number of small spindle motors salvaged from old hard drives that
have only 3 connections. As far as I can tell using my VOM, the 3 coils do
NOT have a common ground connection......or at least I can't find one.

Can someone describe how the 3 coils of this type of (brushless) motor are
driven to make the motor run? I am familiar with HD motors having 4
connections, and there are a number of handy DIP IC's to run this type of
spindle motor, but is there an equivalent IC for use with these 3 coil HD
motors?

Thanks
Jim


It is a 3 phase motor, feed them with some voltage approximating

that, and it will turn, even if you use square waves, if each
is shifted 1/3 period.
The center point to which the 3 windings are connected, can be
floating.

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