Author Topic: Anybody use combined bench dmms like this?  (Read 648 times)

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Offline 001

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Anybody use combined bench dmms like this?
« on: April 14, 2018, 07:53:37 am »
LOL

It is vintage russian bench multimeter
ADC is 7107 clone + analog bar (with separate autorange circuit) :)

Is it good idea or not?


PS - it equipped with active  HF  probe (vacuum diode inside it)
« Last Edit: April 14, 2018, 08:52:30 am by 001 »
 

Offline EE-digger

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Re: Anybody use combined bench dmms like this?
« Reply #1 on: April 14, 2018, 08:34:05 am »
LCD is cracked at one end but could continue working for years that way.

Does it do what you want?  The analog meter can be helpful when making an analog adjustment or observing audio peaks, etc.  Various DMMs implement this with a digital gas gauge at top or bottom of the readout.

The advantage of your analog meter is that it has infinite resolution  :)
 
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Offline 001

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Re: Anybody use combined bench dmms like this?
« Reply #2 on: April 14, 2018, 09:15:21 am »
Do you know some analogs from hp and others?
 

Online DaJMasta

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Re: Anybody use combined bench dmms like this?
« Reply #3 on: April 14, 2018, 09:29:10 am »
The advantage of your analog meter is that it has infinite resolution  :)

And finite precision to the point of not getting higher effective resolution than what you can estimate given the printed scale, but there's no reason to start this argument here.


I think because of the size/shape of a readable analog dial, benchtop meters in this form factor were not so common when they were still in fashion.  Most higher end analog meters you find are in the "handheld" style even if they're a bit big for that, and while you occasionally find combo meters like this one, once the manufacturer went digital, they generally didn't bother.  You see them in older RF power meters sometimes, but multimeters are generally one or the other and what we think of as standard bench form factor meters are almost all digital.


If you can test it and verify it's in good shape, I don't see why you can't use it - and there's probably ways of adjusting trimmers and such to get it back in spec if it's drifted around.

Offline EE-digger

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Re: Anybody use combined bench dmms like this?
« Reply #4 on: April 14, 2018, 09:56:08 am »
No argument, I agree.  It can still be handy for peaking or in lieu of an averaging function.
 
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Offline bicycleguy

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« Last Edit: April 14, 2018, 03:32:24 pm by bicycleguy »
 

Offline rhb

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Re: Anybody use combined bench dmms like this?
« Reply #6 on: April 14, 2018, 11:31:48 am »
VTVMs were very definitely not "hand held" unless you had *really* large hands.  Not light weight either.  The best you could get in a VOM was 50 K ohms/volt.  A VTVM was 10 M ohms/volt.   But you paid a price for having a tube and HV PS.

If you want an analog meter, adding an FET input to a $3  1k/v meter is easy, cheap and makes them usable for low voltage.  A high impedance FET VM was a popular project in ARRL handbooks 30 years ago.
 

Offline 001

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Re: Anybody use combined bench dmms like this?
« Reply #7 on: April 14, 2018, 03:32:11 pm »
The analog meter is placed here after wide band rectifier (using opamps) and autorange circuit
 

Offline Performa01

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Re: Anybody use combined bench dmms like this?
« Reply #8 on: April 14, 2018, 09:00:03 pm »
Here's a posting that has the image of a high quality combined analog/digital (handheld) meter attached:

https://www.eevblog.com/forum/testgear/(quiz)-what-is-it/msg286689/#msg286689

Metrix quite obviously gave priority to the analog meter, size-wise ;)
 
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