Connect both the ground and the hot probes of the scope using two 1uF non-polarised caps, rated 150V each, and two resistors, each 1k 1W. You make two groups, each with a resistor and a cap in series and you connect each group to one scope lead (one ground one hot). Peter -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu