Electronics > Beginners
Circuit(s) to teach basic oscilloscope functions
vk6zgo:
--- Quote from: IDEngineer on February 18, 2020, 12:50:05 am ---
--- Quote from: RoGeorge on February 17, 2020, 09:52:27 pm ---Any oscilloscope have a square signal generator for probe calibration. That signal should be enough for teaching the basics.
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I'll add a vote for a function generator. A square wave by itself does not really allow visualization of varying trigger levels. You need something slower than a square wave's edges for that, like a sine or triangle/ramp. Then you can literally watch the waveform "move" as the trigger level is varied. This makes the behavior of the trigger instantly intuitive. IMHO the trigger is one of the most powerful aspects of a scope, and it's important for newbies to really grok what is happening.
Another handy signal source is any sort of analog video camera, as is found in (far too many?) devices these days. Almost all scopes have H and V triggering which handles holdoff, allowing a single line or frame to be easily displayed. Zooming in and out (with the timebase) while triggered makes the horizontal sweep timing very clear, and the ability to wave your hand around in front of the camera and "see" the effect on the analog video data is another very intuitive demonstration. People can relate to video cameras since they're surrounded by them these days.
I've done the above in under 10 minutes with utter newbies - never touched a scope before - and they were then able to describe and demonstrate how a scope works to another newbie. Some of the terminology wasn't quite right, and they fumbled with the controls, but they *understood* what was happening and could demonstrate it given enough time. That's a win in my book for <10 minutes invested!
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Get them to look at field rate analog TV signals, by all means, but better use a pretty decent DSO or an analog 'scope.
A very cheap "pretend" 'scope won't be able to display such signals properly, neither will a very old DSO.
On second thought, a terrible "El Cheapo" DSO compared with a good one, or an analog 'scope might be a good "teaching moment".
You can ask them why the field rate display doesn't work! ;D
David Hess:
I always liked switching regulators for testing the basic functionality of oscilloscopes. Triggering on or displaying the reverse recovery waveform of the rectifier is a good use for delayed sweep and trigger after delay.
pixelkind:
Thanks a lot for all the input!
I like the button bounce a lot. Also the RC oscillator.
We have function generators but I prefer some "real" circuits to show as well.
tunk:
Could this be an alternative:
https://www.velleman.eu/products/view/?id=387510
pixelkind:
--- Quote from: tunk on February 18, 2020, 08:59:22 pm ---Could this be an alternative:
https://www.velleman.eu/products/view/?id=387510
--- End quote ---
Very interesting. Thanks a lot
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