The wires were short, just to the breadboard, while the USB cable was a standard 1.8m (though this probably didn't make a difference). This evening I'll try to rig up a few 1 meter wires to start some real testing. But it's good to know about the caps. Is there a rule about the cap size vs wire length?
Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.