Jumper JP3 (USB power to target)There's a jumper sticking out near the cables, JP3. When the jumper is in place (connecting the two wires) then that means that the USBtinyISP is providing 5V power to the device being programmed. If you don't want to power the device then just take the jumper out or make sure its only on one of the wires.The USBtinyISP can only provide 5V, up to about 100mA to the device. If you need more power then you should remove the jumper and power the device seperately. (Alternately, if you're feeling adventurous you can reprogram the USBtinyISP to requires 500mA from the USB port instead of 100mA but if you dont know how to do this I'd suggest not)Version 1.0 of USBtinyISP sends data to the device at 5V level no matter whether its powering the device or not so make sure its 5V compliant! (Note that there are 2 1.5K resistors in series with the data lines for protection)Version 2.0 which is almost certainly what you've got, uses a level shifter so that if the jumper is not in place, it will use whatever the target voltage is, a lot better for your low-voltage devices!So, if you have a device that needs to run at 3.3V or so, don't have the jumper in place!