Thinking about it more, Maxim also makes a "flying capacitor" isolator that could be used. Then Analog Devices (I think) makes isolation amplifiers. Someone else also mentioned differential amplifiers. AD (again, I think) has one that will handle a couple hundred volts common mode. Harold _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]