Single HD Gyro Image stabilizer

Step 4 Electronics

A HD needs 2 or 3 voltages (3-4 leads) to function( 12V, 5 V, the newer SATA disks also 3.3 V, and of course ground/ 0V).

Most older HDs, the ones with a Molex connection, only need 12V and 5V. Although the spinning motor needs only 12 V, the HD won't work unless it is supplied with both voltages.

Power requirements for any model HD can usually be found on the sticker at the top of the HD, or on the manufacturers' site.

Cheap (2 E) USB car phone chargers transform 12 V DC into 5 V DC. The output of a single charger is ca. 400 mA.

2 of these chargers were wired in parallel, to meet the start-up power spike requirements (the arm of the HD only makes a few moves during start-up; afterward it doesn't do nothing).

My power supply is a small 12 V lead acid battery. A ca. 1m (3 feet) flexible wire ending in a car 12 V socket supplies it to the device. The battery can be worn in a small shoulder bag or on a waist belt. Plugging it in or out is the 'on/ off' switch.
(Other types of 12V batteries are possible as well; with a setup looking quite different).

The car phone chargers come in a ' car plug' format. After the circuit boards were soldered in parallel, one plug was left intact, while part of the housing of the other one was put behind it. Some hot glue, duck-tape and a piece of bike inner tube made it more sturdy : almost like a laptop power supply!!!

Comments

[mpritchard4]

SATA drives ought to still run on 5V and 12V, otherwise the Molex-to-SATA converter leads wouldn't work. Nice tutorial!

I've been playing with an old Seagate five-platter SCSI drive today, poking and prodding the TPIC1533 motor drive IC. Unfortunately whilst the motor runs on 12 volts, and one side of each driver (pulling the motor wire down to ground) uses 12 volt pulses, the other side of the driver (pulling the motor wire up to 12 volts) uses pulses of 24 volts so that's yet another supply rail to deal with! Obviously other drives may be easier (or harder) to control, but for this old Seagate I need a 6 phase, 480Hz, 12/24 volt power supply so it's a job best left to the drive itself!

Swings and roundabouts with faster drives, too. 10K drives have slightly smaller platters, 15K drives smaller still (think 2.5" platters in a 3.5" drive and you get the idea) so the increased gyro speed (and whine) is countered by the decreased spinning mass.