> > Of course, an ordinary voltmeter will never see these very brief stutter > pulses. > I have a Fluke 336 voltmeter that has the in-rush current feature. It has never indicated any large surge for our Furuno GP32 GPS. We had an issue with the GPS that Furuno claimed was bad power, it was actually a bad GP 32 GPS The GPS would "hang" on boot up. I measured the voltage and current probably 15 times with them on the phone telling me their GPS only hangs on from a too low voltage source, hence I must have a low power problem. They sent me a new one and that one has never hung. I have an oscilliscope currently on board our boat. (Before anyone gives me grief about why do I have one... How they crossed the world years ago and never needed one etc... Unlike what the recent Passage magazine article says about European Power, I find 380 volts to be pretty common on the docks for 50 ft power boats. Since nobody has written about it, I am researching it to get a better understanding of it. I have It to help me understand what happens with mis-wired 380 volt shore power plugs what does the wave form actually look like when mis-wired.) Could one the electrical engineer's about tell me how to best measure the in-rush current on a small electronic device using my 10 megaHz o-scope?

Scott, To measure the "in rush" current in any instrument install a very low resistance device on the power cable and measure the voltage drop across it with your scope. The size of the resistant will depend on the current level that you wish to detect and the maximum sensitivity of your scope. The lower the resistance the better from the view point of having the smallest possible effect on the operation of the equipment. (A short piece of number 16 wire maybe enough. John Harris