Well, I found an old wall wart rated at 9VDC @ 300mA Output. I cut the end connector off, and replaced it with a 9V battery connector. I'm trying to use it as a replacement for the 9V battery on my BASIC Stamp Board. I plugged the snap connector into the battery prongs of the BASIC stamp board. Then nothing happened! I Measured the output of the wall wart while connected to the BASIC Stamp board, and was reading 15VDC! My BASIC Stamp board still worked after that endeavor just with the 9V battery. I infer that the transformer needs to be loaded down with a resistor?
Need a six volt drop at 300mA
R = (15 -9) / 0.3A = 20 ohm Resistor
Am I correct? Please help