In the voltage measurement options along with Peak to Peak voltages there are "RMS" and "Cycle RMS" By turning on either one I get some 10-20mV RMS readings What do you get from these values if you don't know the shunt resistance? I don't get it. I also have not been able to get a solid waveform when scope leads are connected across the shunt between the MOSFET source and minus. Only random noise. I suppose I don't understand something here