DIY hard drive clock (intro)

Hard drive clock. New life for old junk.

Technical idea is pretty old but making things is fun and hard drive clock itself is very cool and entertaining device.
It's quite easy to build one and I'm sure that most  DIY-makers have some unwanted PC hardware that can be easily put into service again.

Obsolete hard drives. Are they good for something?

Beside hard drive itself, for this project we need microcontroller, real time clock, photo interrupter or Hall effect sensor and bunch of RGB LEDs. All this stuff is widely available. 


I've dug trough my personal pile of obsolete hardware and fished out excellent external SCSI hard drive.
It contains lots of useful parts that can be reused for this project:
- hard drive;
- solid metal case with rubber feet;
- LED power indicator at front panel;
- power plug and switch at the back;
- switch mode power supply +5V, +!2V;
- 12V fan.

Useless old external hard drive?  Nope, it's a box full of treasures.

Hard drive have to be vandalized because we are going to reuse only spindle motor with two disks and controller board. 
From my experience, some hard drives shut down spindle motor if there's no signal from magnetic heads.
For that case there are few possible solutions:
- tweaking disk controller by rerouting corresponding signals (if data sheet is available);
- using custom build controller for brushless motor;
- getting another hard drive. 

DIY hard drive clock ---> (part 1)