... that's what they built 'scope hoods' for ... Seriously - turn the lights down low, concentrate on just those particulars of the waveform you are measuring (amplitude - does it pass above or below known voltage reference points on the CRT, time - does it exceed or fall short of the expected period) and note if this non-periodic waveform meets that criterion. This may take a number of attempts, but lacking a digital storage scope this has been the tried and true technique used in the past ... based on the fact that (most!) all CRTs exhibit some 'persistance' (or lingering luminosity of the display) due to the 'trace' that details the waveform. I don't recall if the 'old' Polariod scope cameras (with the shutter held open) were any good/fast enough at capturing these kinds of waveforms or not ... Jim ----- Original Message ----- From: "Donovan Parks" To: Sent: Thursday, April 18, 2002 8:21 PM Subject: [EE]: viewing non-periodic waveforms with an analog scope Hello, I have a Tektronix 465 analog scope and it works wonderfully for viewing periodic signals. I've now come to the point where I need to view a 40kHz square wave that lasts for only three periods (and thus is non-periodic). I can set the scope to single sweep mode and get it to trigget on the first rising edge, but the signal disappears far to fast for me to analysis it. Turning the time base down doesn't help as the width of the signal shrinks in proportion. Is there any way to use an analog scope to view this waveform? Would a digital scope solve my problem (I could at least try and capture the screen with a digital scope)? What do others do when trying to observe non-periodic waveforms? Thanks, Donovan -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics