This post is a follow on to another thread that discussed how to recover a "bricked" ATTiny chip, such as an ATTiny13, 24, 25, etc. Since posting a solution there, I've refined my design a bit more to include a "charge pump" circuit that generates the 12 volts needed to reprogram the fuses using the HVSP programing mode. The unique thing about this new circuit is that the change pump is built entirely from basic components and does not require an exotic (expensive, or hard to obtain) IC to generate the 12 volts. Instead, it uses an interrupt routine that runs in the background on the Arduino to drive a Dickson Charge Pump. The extra circuitry needed consists of 4 diodes, 4 capacitors, 3 resistors and a 2N3904 transistor. If anyone finds this useful, please let me know.
https://sites.google.com/site/wayneholder/attiny-fuse-reset-with-12-volt-charge-pump
Wayne

