ATtiny13 Led Stars There are source PCB drawings, Source and hex code files, Proteus simulation files. Added transistors to increase the number of LEDs. There are three printing options in the files. According to the scheme: instead of LEDs through a 1kOhm resistor to the base of the NPN BC547 transistor, then the LEDs are simply in parallel. Current limiting resistance – 47 Ohm. Fill is used as a plus and not a minus as we are usually used to (I don’t know why it happened, well, how it happened).
In the archive of materials there is a third design option, double-sided, for two-color LEDs. We just made the transition to the other side and added four more LEDs for each beam. This gives a total of 8 LEDs per transistor. When I made a board in DIP packages, I sawed grooves under the LEDs and they illuminate both sides of the star. And then the idea arose not to saw the grooves, but to make two sides of different colors. If you put it on a rotating Christmas tree, or just hang it on wires, it will turn to the viewer in different colors.
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