Scopes with delayed sweep?

Any and all.

O2 sensor, for starters

trigger it off the tPS signal, blip the throttle and watch for the O2 sensor to react

ditto the injector pulse width's

I found this in the archives (had searched before but didn't pick it up)

"Time Base Selections

Your oscilloscope has a time base, which is usually referred to as the main time base. Many oscilloscopes also have what is called a delayed time base ? a time base with a sweep that can start (or be triggered to start) relative to a pre­determined time on the main time base sweep. Using a delayed time base sweep allows you to see events more clearly and to see events that are not visible solely with the main time base sweep.

The delayed time base requires the setting of a time delay and the possible use of delayed trigger modes and other settings not described in this primer. Refer to the manual supplied with your oscilloscope for information on how to use these features."

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So is delayed sweep mostly used in delaying one chan vs the other? That I can follow with say an injector PW and O2 sensor (could be quite useful)

But there seems to be implication that delayed sweep is also used with just one channel, "to see events more clearly" - why can't just a different time base be used for that one channel (faster, to 'stretch' the waveform out)

Lance

Not necessarily. Think of it as an electronic magnifying glass that you can apply to any short section of a waveform on the main sweep, or a waveform that bears a given time relationship to what's displayed on the main sweep.

Consider a one horizontal sweep of a TV signal. There's all kinds of detail in there that's way to small to make out. Use a faster timebase and you get a better look at the start of the waveform, but suppose it's something near the end you want to observe? The only constantly recurring event is the blanking pedestal, all the rest is dancing all over the place and you can't synch off it.

Now on a car you could trigger from say a capacitive signal obtained from a bit of foil wrapped around the #1 spakplug. Your main sweep could be showing you the signal from the #3 cylinder's plug, but it would be a spike a considerable distance along the sweep. Using delayed sweep you could fill the whole width of the screen with just that spike. Or you could be picking off a fuel injector waveform and zeroing in on that. Or with a multi-channel front end you could have four timebases with a different signal on each.

Thanks much, John (and for the e-mail). Great explanation that cleared things up. I've been missing out in using scopes w/o the feature (my next scope will have it)

Lance