2016-03-22 20:47 GMT+01:00 Noel Chiappa <jnc at mercury.lcs.mit.edu>: Don't work with lethal voltages! Use a insulation transformer. Then it is not as likely to kill you unless you brake the rule and put both your hands in the supply. Then use a variac. My experience is that you can observe the behaviour at a much lower voltage when the load is small. This supply if I remember correctly will work fine from 60 VDC at the input caps. I do this all the time. I am not nervous when putting the scope-probe on anything in there. One more thing regarding the H7104. The circuit that enables the relay will also enable the signal to the main chopper transistors. Thus there will be no switching at all unless the input voltage is above 250VDC or so. I disabled this circuit for testing purposes. As long as the load is small this should not cause any problems. (And since I tested I know it didn't) /Mattis