Hard Drive Clock using PIC16F628
ave an old hard drive that no longer works? As long as it still spins up chances are you could build a clock out of your old hard drive!
You will need some electronic knowledge, some common electronic components and a bit of
patience. The clock that is produced isn’t exactly practical since most hard drives (especially older ones) are too loud for a clock that is to operate 24 hours a day.
Watch a video (1.5MB) of the clock in operation!It takes the clock a sew seconds for the speed to stabilize, during this time there is a random pattern of lights that is displayed. After this the clock starts up. It is shown starting at 2:40:00.
Another video (4.7MB) this one shows the clock time being set.Three buttons on the back allow clock adjustment. The purple second hand resets to the zero mark when it’s button is pressed. The blue minute hand increments through each minute and the red hour hand increments through each hour. The position of the hour hand is also dependent on the minute hand. For example the time is 2:30 the hour hand will be pointing at the 12 minute mark.
- Uses 12 high power LEDs for displaying the clock hands, 6 Blue and 6 Red.
- Slot cut into upper drive platter and white tape on center drive platter provides a slot that when illuminated by the LEDs will represent a clock hand.
- Minute hand is represented by blue light, hour hand is represented by red light and the second hand is represented by purple (both blue and red on at the same time).
- Infrared Beam sensor and drilled index hole in lower drive platter.
- Three micro switches to set hours, minutes and seconds.
- Custom programmed PIC16F628 microcontroller to control clock operation.
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STEPS TO CONSTRUCT CLOCK
1) Select Drive: Find an old hard drive that can spin up when power is connected, you may have to disconnect the 40 pin data cable to see that it can spin up. The drive must spin counter clockwise.
2) Open Drive: Open the drive and see that there are three platters in the unit. We will need three since the top one will have a slot cut into it, the second one will have a piece of white tape (or some other highly reflective material attached. And the third platter will have an index hole drilled into it, this index hole will be used to determine where the slot is when it is spinning. It could still work using a two platter drive but the top of the infrared beam sensor would be visible when a hand is over it.
3) Cut Slot: Remove the screw in the center of the platters, this should allow the platters to be removed. Cut a slot into the 1st platter, I clamped the platter into a vice protecting the surface with cardboard so it wouldn’t scratch. A grinder was then used to cut the grove. It was very easy to cut since it was made of aluminum. NOTE: The top platter that I ended up using was from a more modern drive. The older drive had platters that were dark brown and not very reflective, the modern drive had platters that had a silver mirror finish.
For more detail: Hard Drive Clock using PIC16F628
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