Hacked Gadgets Forum

December 12, 2008

Rotating Blue LED Display

at 11:12 am. Filed under Complex Hacks, Cool Gadgets, Electronic Hacks


Thanks to Csaba for sending in this very nice looking display. The frosted blue LEDs have a great effect!

Project code (zip).

An old tape recorder motor. With this load it can rotate about 7.4/s. The image is flashing, it should rotate about 25/s. For supply a 7809 IC is used.

Supply of the rotor
The commutator of another similar motor is used (crw_1511) and a 3 phase rectifier with a big capacitor (crw_1510). For supply a 7806 IC is used shifted with a diode, so the supply voltage for the uper part is 6.7V. The rectifier voltage (1.2V) is subtracted from it.

8 pieces of 5mm 3000mcd blue leds. The body is made to be diffuse by sandpaper, so the viewing angle is much larger. The bottom is painted black, so there are no additional light spots.

PIC 16F84 microcontroller @20MHz.

The displayed picture can be edited in Excel pixel by pixel. The Excel table is divided to character spaces (5×8 + 1 column spacing) but any graphics can be displayed. 100 columns are displayed, but 250 can be edited. If the jumper is on, than the first 100 column will be visible and not moving. If the jumper is off than the 250 columns will slowly be shifted through the displayed area.

The output of the Excel sheet should be copied into "data.inc" and the software must be rebuilt and downloaded.

The LEDs are driven through a 100 ohm resistor directly and the supply can be turned on/off by a FET. An optical sensor is used to get position info. (Dismounted from an old floppy drive.)"