http://www.stormcam.org/adapters-pack/
Why do all “wall-wart” adapters seem to be the wrong voltage?
I have a drawer full of those “wall-wart” AC to DC adapters. Most of them are labeled “9V”, some are “6V”, and a couple are “3V”.
So here’s my dillema. I have a device that runs off of a battery pack, and to save on batteries, I figure I’ll reuse one of these adapters. The device runs off of 6V DC (usually 4 D cell batteries). So, I find a 6V transformer that has the right plug (polarity is correct and all), and I plug it in. No dice, the light goes red indicating something is wrong with the power source. So, I pull out my multi-tester, and come to find out, this little 6V transformer is putting out 11.5V! I test my others, with about the same results (within a volt or two). I test some 9V adapters, and they are putting out between 14 and 16 volts! No wonder the thing isn’t working correctly, I’m lucky it didn’t burn out! I have heard that these things often operate within a tolerance of about +-10%, but we’re talking about a consistent 50% to 100%! What’s going on here?
The voltage rating is the voltage output when the wall-wart is connected to the load it is rated for, usually expressed as milliamps on the label. To get an accurate reading you would need to measure the voltage while it is plugged into your device. Chances are you will find that the little wall-wart is putting out LESS voltage than the device needs.
Studio on my back pack job