Out of various DIY devices contributed by Alan Parekh, there is a project named ‘Hard Drive Clock’ which can be considered as an interesting medium to put the electronic concepts to use. The name of the device itself implies that it can be built from an old hard drive, which can’t be used otherwise. This clock makes use of LED lights that denote the hands while the setup is controlled by a custom programmed microcontroller. Some other essential components include three micro switches and an infrared beam sensor.
First and foremost, Alan took an old hard drive that could spin in a counter clockwise motion. Then he opened the drive to get access to the three platters fitted inside and removed the screw in the center. He cut a slot into the first one with the help of a grinder and put a white tape on the middle one that served as a slot to represent the clock hand. Moving on to the third one, he drilled a ¼ inch hole near its edge and positioned the infrared beam sensor around it. The sensor was in the shape of a horse shoe fitted with an infrared LED on the first half and a phototransistor on the second.
There is an important role of phototransistor in the functioning of the clock. The LED keeps emitting infrared light (invisible to naked eyes) and then the phototransistor allows the circuit to sense if the beam is broken or not. Here the index hole helps in interfacing the device with the platter assembly and the PIC chip easily detects the location of the rotating platters.
After this, Alan marked and drilled holes halfway between the top and center platters in order to make way for the LEDs. It is important to note that these LEDs should be super bright so as to cast a good beam. One may remove the read write assembly by cutting off its arms or can keep it unaltered. In the next step, he installed the infrared beam sensor at the lower right area of the disk drive in a way that it could see the index hole on the third platter. This sensor could also be availed from some commonly used devices like a fax machine, floppy drives, etc.
Later, he constructed and mounted the circuit board on the back of the hard drive. The wires were connected in the desired manner linking all the parts like LEDs, sensor and the power input to the circuit board. Finally, he downloaded the PIC microcontroller code and burned it onto the chip using a programmer.
After the complete procedure, Alan also suggested certain improvements that could impart a better appeal to the clock. Instead of putting large LEDs on the surface, one could mount smaller LEDs on a strip and then attach it to the inner radius of the clock. This would eliminate the need for an ugly cover or the unnecessary holes drilled all over the surface. Moreover, instead of a simple design, a stylish pattern could be drawn.
If you wish to try your hands on a similar device, the following link contains all the steps in detail along with the videos that can be accessed for gaining a better insight of the project.
Filed Under: Reviews