EEVblog #876 - NI VirtualBench Review

[TheCharels]

When you are inexperienced it is not that hard to break test equipment.

The DMM:
Vaporized a probe set measuring mains voltage in 10 amp AC current mode.

Results:
Buy a replacement probe set. DMM no damage. Quite the surprise though.

The oscilloscope:
Probing an X10 appliance module and connecting the probe ground to the circuit ground then plugging in the X10 module.

Results:
Lots of sparks and magic smoke from the oscilloscope. This was expensive enough. I would not like to do this on equipment that costs US$6000.

The power supply:
Use constant current mode to charge a 2 amp hour NiMH 7.2 volt pack then try to CC mode to try to discharge the pack.

Results:
Internal fuse and reverse voltage diode blown. No sparks or magic smoke.

These are just mine for that course. But then I must not be that bright.

[rs20]

When you are inexperienced it is not that hard to break test equipment.

The DMM:
Vaporized a probe set measuring mains voltage in 10 amp AC current mode.

Results:
Buy a replacement probe set. DMM no damage. Quite the surprise though.

The oscilloscope:
Probing an X10 appliance module and connecting the probe ground to the circuit ground then plugging in the X10 module.

Results:
Lots of sparks and magic smoke from the oscilloscope. This was expensive enough. I would not like to do this on equipment that costs US$6000.

The power supply:
Use constant current mode to charge a 2 amp hour NiMH 7.2 volt pack then try to CC mode to try to discharge the pack.

Results:
Internal fuse and reverse voltage diode blown. No sparks or magic smoke.

See, this is my point:

DMM: Any half-decent DMM will scream at you if you switch the multimeter to Volts mode while the probes are plugged into the current jacks. Also, it's extremely bizzare that the leads blew and not the fuse. Sounds like the fuse didn't do its job. Conclusion: you had crap gear.

Oscilloscope: I don't quite understand what X10 means, but I gather that you, in effect, connected oscilloscope ground to mains live or mains neutral? That should have tripped the GFCI instantly. Did this lab really not have GFCIs? Yikes! Was this a proper university electronics lab, or some random person's basement?

Power supply: Fair enough, that's just an awful thing to do to a power supply. But here I take your point, I asked for an example of something non-contrived and horrible that students could do to hurt good quality lab equipment, and this is the one example you've provided that answers my question.

[tszaboo]

I am struggling to understand why any establishment, educational or otherwise, would purchase this rather than traditonal bench gear.

The only benefit as far as I can see is that it's a single integrated unit, but it's a very expensive one. Possibly LabView integration too? I don't know, but personally I take a great dislike to the bloatware from NI that gets installed on my PC just to run a few SCPI commands. I would imagine that hardware designers are not their target audience though, LabView seems more targeted to production and process control systems rather than electronics R&D.

I can imagine the marketing model is much like Matlab. Almost give it away to education, then the studes become dependent on it. While big corps might consider it, it'll be an almost impossible sell to an SME who'll see value elsewhere. Having said that, I love their MultiSim Touch tablet app for circuit simulation which is cheap as chips.

Probably they give it to universities for free. At least I would not be surprised. There are companies donating entire labs to unis, just to get their name into the student's mind, when they search for a job. Kinda makes sense. There are countries with hundreds of job openings for engineers at a single company.

[Macbeth]

Probably they give it to universities for free. At least I would not be surprised. There are companies donating entire labs to unis, just to get their name into the student's mind, when they search for a job. Kinda makes sense. There are countries with hundreds of job openings for engineers at a single company.

This reminds me of Nestle and the free baby milk scandal. Once the young mothers in third world countries had left Nestle funded maternity wards just when their breast milk dried up, they were then thrown out on to the streets and forced to beg, borrow, steal and prostitute themselves just to pay for formula.

Sorry Nestle Instruments, weaning college kids on your stuff like this is criminal. I am uninstalling NI-VISA in protest now at you evil capitalist bastards. Right up there with Monsanto, Goldman Sachs, the FED, the Rothschilds and Bilderbergs.

[tszaboo]

This reminds me of Nestle and the free baby milk scandal. Once the young mothers in third world countries had left Nestle funded maternity wards just when their breast milk dried up, they were then thrown out on to the streets and forced to beg, borrow, steal and prostitute themselves just to pay for formula.

Sorry Nestle Instruments, weaning college kids on your stuff like this is criminal. I am uninstalling NI-VISA in protest now at you evil capitalist bastards. Right up there with Monsanto, Goldman Sachs, the FED, the Rothschilds and Bilderbergs.

Sorry, what?

[Macbeth]

Sorry, what?

Sorry, just my strange sense of humour. ... I'll get me coat ... 

[Kleinstein]

Normally the instrument should be pretty robust, but with a beefy inductor and the supply current voltage might exceed the about 200 V maybe 300 V limit for the scope if you don't use the 1:10 probes but direct 1:1 connection.  I once blew an scope input amplifier with to much voltage testing with an 1:1 probe AC coupled in a tube circuit, that had something like a 150 V DC offset. The problem was likely the input cap was also storing voltage and that got added to exceed the 250 V Limit. I hope USB GND is Isolated from the measurement functions - this could also cause quite some trouble.

The other weak spot might be the digital IO / function generator outputs and 50 Ohms termination. They might not stand the 25 V from the supply. Especially both supplies in series could well be a problem.

Modern DMMs are pretty robust . So I won't expect a problem there, especially as in education you are normally not using mains voltage.

[jitter]

This reminds me of Nestle and the free baby milk scandal. Once the young mothers in third world countries had left Nestle funded maternity wards just when their breast milk dried up, they were then thrown out on to the streets and forced to beg, borrow, steal and prostitute themselves just to pay for formula.

Sorry Nestle Instruments, weaning college kids on your stuff like this is criminal. I am uninstalling NI-VISA in protest now at you evil capitalist bastards. Right up there with Monsanto, Goldman Sachs, the FED, the Rothschilds and Bilderbergs.

Sorry, what?

It's the "Happy Meal thinking" I was referring to. Include a toy in the meal and not only do you get the children to want to go to McDonald's again and again and again, that name will then be engraved in their brains for the rest of their lives. My parents didn't do this to my brother and I, but I did work there part time for almost eight years in my young days, and I have seen first hand what those seemingly innocent toys can do...

You always need to get people to want more. That's why those big corporations do stuff we wouldn't really approve and it's why NI didn't include the full functionality in the standard VirtualBench UI.