prop clock

Posted on Feb 6, 2014

Propclocks are really pretty complex devices, utilizing a PIC microcomputer that performs instructions at 10mhz. The PIC is the brain of the device and does most of the work involved in making the LEDs light up at just the right time so that it appears there are numbers, and in the analog mode hands suspened in mid air. On my version of the clock you change the mode and time setting

prop clock
Click here to download the full size of the above Circuit.

while it is still spinning at about 1150 PRM. This is done through carefully alligned photo detectors and LEDs. These sensors are located on the rear of the spinning motor so they dont affect the look of the clock at all. (the below diagram should explain it) This is a link to the diagram i made, it shows how the whole thing works, and what makes my clock different from anyone elses i have seen sofar. (you better like that diagram cuz it took me about 5 hours to make :) Here is an actuall photograph of the backside of the motor assembly. You can clearly see the standoffs and the acrylic stand for the coils and stuff, what you can also see in this picture is the secondary coil which is 200 turns of 28 gua copper wire, its the black thing wraped in electrical tape. Sticking our from the center of the secondary is the IR sensor which is used for changing the mode. The other sensor that is only sensitive to visible light was also mounted as close to the center of the spindle as possible with hot glue. Also the primary coil is located above it, i only wraped it in electrical tape in 3 spots because i thought this would improve cooling. It only gets slightly warm though so this probably wasnt needed. Here is a scann of the back of the clock, yess i actually layed the whole thing down on the bed of the scanner :). The barely visible acrylic triangle is spaced from the back of the motor with aluminum spacers, it has the primary of...

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