I bought an Arduino Uno a few days ago.
I programmed an ATtiny45 using an Arduino Uno following "How-To: Shrinkify Your Arduino Projects" video on YouTube.
I uploaded the blink example successfully. I altered the sketch in a way so there is also a blinking on pin 4 (which is ATtiny45 pin 3).
Now, if I connect +5V from the Arduino to ATtiny45 pin 8, ground to pin 4 and the LEDs from pin 2 and 3 to ground everything works as expected.
But if I use 4 AA batteries instead of the power from the Arduino I only get a blinking on ATtiny pin2.
What could be the reason for this behavior? Is it because I use 4 AA -> 6 V instead of 5 V? I tested it also with 3 AA batteries and got the same result.
So why does it work if I use power and ground from the Arduino but not from the batteries?