I have programmed my Attiny with an Arduino UNO with ''Arduino as ISP''.
The program is just Blink to pin 4 on my Attiny.
Problem lies here:
When i have connected just pin 8 to Uno 5v, and pin 4 to Uno GND, everything works perfectly fine and my LED blinks every second.
BUT, when i connect pin 8 to power supply + and pin 4 to power supply -, all hell breaks loose.
Diode does a blink or two just fine, but then the timing is messed up and blinks rapidly. The power supply is set to 5V.
Any idea what may cause the problem?