pov-1.png (60277Bytes)
pov-1.jpeg (212614Bytes)
100_0793.JPG (905527Bytes)
pov.zip (23801Bytes)
A number of years ago I built a clock style POV as an example of making PCB's at home. It used a PIC16F1320, 7 LEDS, 9V battery and associated power components on the PCB and a scrap DC motor to rotate the device. After the talk I reprogrammed the message to display a friends business name and gave him the unit. After about 5 years it came back. Not working.
Another well known LMR member has also made a POV. After multiple pleas with him to repost his project I am posting mine.
Just PCB artwork for today. This time I went with a slightly more powerful CPU (pic18f2620), 10 LEDS, and lipo battery. The unit is approx 5.4 x 1.6 inches (13 x 4 cm). Uses the existing base and motor. Should this board get spinning, it will be returned to friend and I will start on another model using programmable LEDS.
Update July 1,2015
The boards arrived from the shop. Ordered 10 and they sent 12. Pretty good delivery time, excellent price at $31 US including shipping. Look just like their picture.
Have a few minor problems:
- I ordered thru hole battery case. Layout called for SMT.
- Battery case mounting holes slightly too small - fixed with hand drill.
- Wrong spacing on power switch. Applied magic fudge factor.
It always seems to take me three tries to get the PCB correct.
Have some code running that displays hard coded messages on the LEDs. Reworked a 8x5 font table to align with my expected use. Code to update a single 8 led row requires about 2 usec so there is plenty of room to play.
Have not yet mounted on motor. Thinking about limiting the motor RPM to between 180 and 300 RPM. It needs to be fast enough for the POV yet slow enough to allow time for the LEDS to turn off.
Update July 9,2015
It is working for displaying text messages. Up to 28 characters. Rotation is about 1800 RPM. Much faster than I extected. Need to improve the motor speed stability. Next rev will have a radio for debug. A machinist friend made some really nice motor/board couplings that allowed me to get a good balance with little effort.
Much of the jitter in the video is not present live. The motor speed and the camera frames are probably close in frequency.
Update July 14,2015
Added zip file with source code.
https://www.youtube.com/watch?v=82-Dm41-i3g