Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Parpp807-at-aol-dot-com> In a message dated 4/23/01 5:53:15 PM Central Daylight Time, tesla-at-pupman-dot-com writes: << Independent triggering of the scope using the external socket may help if it can be sync'd with the gap fires. >> Malcolm, This spooks me. How do I safely derive the trigger signal? cheers, Ralph Zekelman