No more switchable oscilloscope probes!

[Axtman]

So the Testing and Measurement Alliance (composed of many test gear manufacturers) have decide that they would stop producing switchable oscilloscope probes.

https://tm-alliance.org/blog/2023-03-31/

I use the X1/X10 switch all the time instead of reaching over and adjusting my oscilloscope input. I guess I am glad I have a stash of them saved up!

[Axtman]

Okay I think I just fell for a prank.

[g1]

Very strange. A lot of work for a joke website. It would have been nice if they dated that April 1 instead of March 31.
The address is for Doc Brown's house in Back to the Future.

[Axtman]

I was surprised that I had not heard of the (fake) news before. Usually news like this is all over the forums before it even publically announced.

I am all for a good (harmless) joke. The creator should identify it as such on April 2. It is irresponsible to leave fake news up. What do you want to bet that the test equipment companies received communication regarding this prank. Or that companies increased or cancelled orders of scope probes.

The world is full of fake news and scams. We don't need people creating more deception!

[g1]

I am not sure if any part of that website is legit. I think the whole thing may be a joke.

[mozz]

Yes it's a joke.
https://tm-alliance.org/about-us/

Dexter Reed
Chief Engineer







Bob Finger
Chief People Officer







Woz Wizard
Chief Prankster

[g1]

Bob Pease, Bob Widlar, Steve Wozniak.

Looks like EEV Blog got taken as well. (edit: I see now that the EEV blog article where he introduced the video is dated April 1, so he was just playing it straight)

[Axtman]

My money is on Dave Jones creating the hoax.

[Helmholtz]

I use the X1/X10 switch all the time instead of reaching over and adjusting my oscilloscope input. I guess I am glad I have a stash of them saved up!

I typically avoid using a x1 probe.
Reason is that these load the circuit with 1M in parallel with around 120pF.
In a high impedance (grid) circuit this may significantly lower the signal amplitude and change the waveshape of complex signals.
X1 probes cannot be "calibrated" (actually this means HF compensation) and spoil the frequency bandwidth of the scope.
No sense using a x1 probe with a 100MHz scope if the probe limits the bandwidth to maybe 20kHz or lower.

A x10 probe, OTOH, only means a load of 10M//10pF and can be calibrated/compensated for flat response up to hundreds of MHz.

[SoulFetish]

I typically avoid using a x1 probe.
Reason is that these load the circuit with 1M in parallel with around 120pF.
In a high impedance (grid) circuit this may significantly lower the signal amplitude and change the waveshape of complex signals.
X1 probes cannot be "calibrated" (actually this means HF compensation) and spoil the frequency bandwidth of the scope.
No sense using a x1 probe with a 100MHz scope if the probe limits the bandwidth to maybe 20kHz or lower.

A x10 probe, OTOH, only means a load of 10M//10pF and can be calibrated/compensated for flat response up to hundreds of MHz.

Same. I set the probe on 10x and secure the switch so it can't be set back to 1x. I was actually relieved that they were going to do away with it . Plus, the 10x attenuator protects the input of the scope some when working on tube amps. I still need a good 100x probe though

[Helmholtz]

Plus, the 10x attenuator protects the input of the scope some when working on tube amps.

Yes, but only regarding ACV, not DCV (with AC coupling) as I learned from g1.

[SoulFetish]

Yes, but only regarding ACV, not DCV (with AC coupling) as I learned from g1.

Why is that? Do they use a capacitive divider? in the scope probe?

[Helmholtz]

Why is that? Do they use a capacitive divider? in the scope probe?

With AC coupling the scope uses a coupling cap before its 1M input resistance.
So DCV doesn't get divided.

Each the probe and the scope channel have a voltage limit (e.g. 400Vp or DC). The lower of them applies with x1 or x10 probes.
A x10 probe doesn't increase the scope's limit.
A x100 probe does.

[SoulFetish]

With AC coupling the scope uses a coupling cap before its 1M input resistance.
So DCV doesn't get divided.

Each the probe and the scope channel have a voltage limit (e.g. 400Vp or DC). The lower of them applies with x1 or x10 probes.
A x10 probe doesn't increase the scope's limit.
A x100 probe does.

If that’s the case, wouldn’t the cap block the DC voltage then?

[Helmholtz]

If that’s the case, wouldn’t the cap block the DC voltage then?

Yes, but I guess that cap has a 400 VDC or 600 VDC limit.

Also when a x1 or x10 probe is connected to a DCV of say 400V, both ends of the coupling cap will jump to 400V producing a 400V transient after the cap.