Digital oscilloscope for high school use

[berkeman]

, I found two oscilloscope cables! They are the type with the probe but will do the job nicely.

Your picture is not of oscilloscope probes...

 

[rsk]

No, these are the Vernier connectors

 

[berkeman]

One other subtlety that you may already know about -- When you use a straight cable (BNC or BNC to clip leads), you set the Coupling for that channel to 1:1, and when you use a 'scope probe, you set it to 10:1 (unless it auto-senses the probe).

Also, if you are coupling a 50 Ohm output signal generator via coax into your 'scope, set the input impedance to 50 Ohms for that 'scope channel. If you are using a 10:1 'scope probe, you will set the input impedance to 1MegOhm.

 

[rsk]

One other subtlety that you may already know about -- When you use a straight cable (BNC or BNC to clip leads), you set the Coupling for that channel to 1:1, and when you use a 'scope probe, you set it to 10:1 (unless it auto-senses the probe).

Also, if you are coupling a 50 Ohm output signal generator via coax into your 'scope, set the input impedance to 50 Ohms for that 'scope channel. If you are using a 10:1 'scope probe, you will set the input impedance to 1MegOhm.

Thanks, I saw mention of the x10 in the probe on one of the videos I watched but had forgotten it.

The signal generator and the scope both have coaxial connections so that will mean either a bit of fiddling or a different cable.

 

[DaveE]

I found two oscilloscope cables!

Congratulations! I guess. After decades of using oscilloscopes, I have no idea what an "oscilloscope cable" is.

have a look at these - they don't fit, do they?

What??? Are you asking us if things that you are actually holding in your hand fit together? Or, fit what?
Electronics isn't an entirely trial and error exercise. Some reading and/or research is nearly always required. Hint: mechanical fit isn't always the only consideration.

Anyway, what's your question here? I can't figure out your post at all.

 

[rsk]

Congratulations! I guess. After decades of using oscilloscopes, I have no idea what an "oscilloscope cable" is.What??? Are you asking us if things that you are actually holding in your hand fit together? Or, fit what?
Electronics isn't an entirely trial and error exercise. Some reading and/or research is nearly always required. Hint: mechanical fit isn't always the only consideration.

Anyway, what's your question here? I can't figure out your post at all.

Oscilloscope cables - the cables which (presumably) were supplied with the oscilloscope.

Regarding the other cables, they physically don't fit together. They are part of a kit with various sensors and a few interfaces, but they don't seem to be compatible. One of them seems to be exactly the reverse shape of what it should be. Just wanted confirmation that I wasn't going mad, that's all.

 

[berkeman]

Just wanted confirmation that I wasn't going mad, that's all.

Well, that's asking quite a lot...

 

[rsk]

Regarding the other cables, they physically don't fit together. They are part of a kit with various sensors and a few interfaces, but they don't seem to be compatible. One of them seems to be exactly the reverse shape of what it should be. Just wanted confirmation that I wasn't going mad, that's all.

We have found another interface unit which does fit the sensors we have, but interface in that picture (we have quite a few of them) don't seem to fit any of the sensors we have. Little stops

Well, that's asking quite a lot...

Probably.

 

[DaveE]

We have found another interface unit which does fit the sensors we have, but interface in that picture (we have quite a few of them) don't seem to fit any of the sensors we have.

The "fit" that matters most are the electrical parameters. Were those devices designed to work with those sensors? IDK. The electronics industry tries to make connectors incompatible (i.e. mechanically won't mate) when they shouldn't be connected, but this really only works within a particular, and common, market segment, like computers.

You need to stop relying on mechanical fit as in indication of electrical compatibility. There will come a time when that will not deliver a good result. Good lab work follows research, analysis, and planning at your desk.

 

[rsk]

They seem to have been bought together and are definitely from the same manufacturer, Vernier, which supplies sensors, loggers and interfaces to schools. However, as above, we have found in another box a different interface which does fit the sensors, but nothing (yet) which fits that little interface.

I appreciate what you're saying about electrical compatibilty, but a mechanical (mis)fit is a pretty good indicator of whether it was meant to be a match or not. School equipment tends to be supplied as easy click-fit to use out-of-the-box.

 

[DaveE]

They seem to have been bought together and are definitely from the same manufacturer, Vernier, which supplies sensors, loggers and interfaces to schools. However, as above, we have found in another box a different interface which does fit the sensors, but nothing (yet) which fits that little interface.

I appreciate what you're saying about electrical compatibilty, but a mechanical (mis)fit is a pretty good indicator of whether it was meant to be a match or not. School equipment tends to be supplied as easy click-fit to use out-of-the-box.

Professional EEs spend a huge fraction of their time researching components, reading documentation, and planning. Good engineering is seldom a game of trial and error, hoping for the best because it seems OK based on limited data. In my lab a part that couldn't be identified by a part number was IMMEDIATELY thrown in the trash.

However, that's not your world of teaching high school with limited resources. Good luck.

PS: I'm reminded of that old grad school joke: Several days working in the lab can save you from spending an hour or two in the library.

 

[rbelli1]

I saw mention of the x10 in the probe on one of the videos

I highly suggest getting some. They add a large impedance between the things you are testing and the expensive test equipment. It takes 10 time more oops to ruin your day.

BoB