Many wall warts are unregulated, a 12vdc wall wart (WW) may have a 21vdc open ckt output. Fully loaded it will be near 12vdc. A WW rated a twice the current may present a higher voltage when lightly loaded than the one that goes with the equipment. Regulated supplies do not have this problem. Watch the polarity of the plug on the LV side. There are NO standards for these. All different voltages, currents & lots of different plugs. Those coaxial plugs was the worse invention. I have high quality equipment & tools with that cheezee coaxial jack on it. Robert
