Hi, i have a 48 led IR illuminator that is powered by a DC12V 500mA mains adaptor. Can i run off a battery pack containing 8 AA 2900 mAh batteries? Will this work or will i need to add in some sort of resistance so the leds don't burn out?
12 volts is 12 volts. It doesn't matter where you get it from as long as you can pull enough current from the supply. Any AA will put out 500ma easy. But you didn't say what type of AA batteries you're using. AA batteries can be anywhere from 1.2 volts to 3 volts each. If you have 2900mah batteries, they're probably 1.2 volt ni-mh, which would only give you 9.6 volts. You'd need 10 of those to have 12 volts.
That should work fine as long as you make sure the positive and negative connection of the battery pack matches the adapter. Your LED unit already has the resistors built in because it is already running off 12 volts DC from the adapter. The above answer is rightrechargeable AA's put out a lower voltage but your battery pack may work anyway (the LED's may be dimmer though).
