"Having seen a few circuits around the web that light up LEDs depending on CPU load I decided to make my own since they do look pretty cool :D I was originally going to have it communicate with the PC using a USB to TTL serial converter, but then I found out about the V-USB library which eliminated the need for a converter and supports ATtiny25/45/85 without the need for a crystal, great!
The ATtiny45 has just enough flash and IO pins for the project, with just the reset pin left (2x for power, 2x for USB, 3x for the RGB LEDs). I obtained a 12V 15 LED RGB strip from Ebay for £5.45 and used ZVN4306A MOSFETs to control them, common transistors like 2N4401 or 2N3904 could have been used instead since each colour only draws around 90mA, but the MOSFETs are more efficient with less heat dissipation and allowing a little bit more current to flow." |