"Propeller Clock" Mechanically Scanned LED Clock

"Propeller Clock" Mechanically Scanned LED Clock
 

Seven light emitting diodes spin, giving the illusion of numbers in the air.

Top View Side View

This is the first clock I ever built. I've built a few LED signs, but they get boring because I already know the message.

How this clock works:

A motor spins the "propeller", and a small microprocessor keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs. It is an illusion, but it works nicely.
If you want to build this clock, you will need a few things, including:

  Skill with motors and mechanical things.

  Prior electronic experience.

  A dead VCR or floppy drive or other source of a suitable motor and miscellaneous parts.
  A programmer that will program a PIC16C84 or 16F84 microprocessor.

I have provided (almost)everything else:

The Next Page with drawings and plans.

Download:

mclock.txt A full description how to build it.
mclkpart.txt The parts list.
mclock8.asm The source code in Microchip MPASM format.
mclock8.hex The hex code ready to load into a PIC16C84 or 16F84 chip.
mclksch2.gif A large and very readable schematic diagram.
mclkmoto.gif A drawing of the modifications to the motor.
If you can't get that kind of motor, you can use the motor from an old disk drive. This page has a lot of pictures and will take some time to load. If you use a disk drive motor or any other DC motor with brushes 180 degrees apart, you'll need the slightly revised code:

Download:

mclockt3.asm The source code.
mclockt3.hex The hex code ready to put in a chip.
If you don't have any way to put the program into a PIC 16C84 or 16F84 chip, you can build your own programmer.
Printed Circuit Board Layout for a version of the clock.

License:

The hardware design and software are covered under the GNU General Public License.

Warranty:

None.

Frequently Asked Questions:
 

Q: What’s this .047 FARAD capacitor?? A: You can get them many places, including memory capacitors at Jameco Electronics. Q: What’s a Berg connector? A: What’s a Kleenex? :-) The PC board side is sometimes called a “header”. The lights and buttons hooking to computer motherboards use them. The pins are .025” square, on .1” centers. The female end is composed of crimp terminals fit into a plastic housing. An example at Jameco. Q: I saw a big version of this at a store but it was different. Have you seen it? A: Yes, I’ve seen a lot of “persistence of vision” clocks in recent years. I made this one in 1996, so I think they all copied me :) Q: My VCR head motor has lots of wires. Which ones do I use? A: I didn’t use a head motor. I used a reel motor. It only has 2 wires and runs on DC.