Including tonal output on a multimeter?

Question

A long time ago, I made a Tonal Voltmeter for low-voltage circuits. Pretty simple, mostly just input from the circuit to a CD4046 connected to an earphone. The idea is to turn small voltage levels into the corresponding tonal output. Like 0 V would be a very low tone and 5 V would be a high tone. When I was doing electronics as a hobby, I enjoyed adding stereo output to the tonal output, but that's another subject.

I always thought that tonal output could be easily added to a multimeter. Just occurred to me you guys would know. So that's my question. It would require a mini 1/8" or whatever jack for the output, or just use a speaker. I guess you would add a voltage-to-frequency converter to the output that drives the LCD display driver or the circuit before that?

I will be more than happy to explain further if I'm not being clear about the question.

Thank you.

David L. Jones · Accepted Answer

Neat idea, and it could certainly be added, but I think the demand for such a feature would be very low, and it's probably not as practical as you'd think. Given that most digital meters are autoranging, and cover a range from mV to 1000V, how would you effectively cover that range? You could have a say a range of tones that was the same for each manual range on the meter, but that would be useless in autoranging mode. You would also have to "train" yourself to what the tones corresponded too, it's just much easier to read the screen and get the absolute value. Needs a hand-off solution where you can't see the screen? Digital meters have had a Touch HOLD function for over 20 years now, and it works a treat.

Dave.

D from BC · Answer

Some DMM models can be USB connected to PC's. One idea would be to write a PC program to do V to F conversion using the USB data. The PC soundcard would make the sounds.

Go nuts and play wav's for different voltages..

5 volts: dogs barking 6 volts: cat meows 7 volts: cow moo 8 volts: birds chirping 9 volts: sirens 10 volts: telephone ring

D from BC

David L. Jones · Answer

100 volts: A voice saying "what's that smell"1000 volts: Automatically triggers your house alarm and calls the firebrigadeDave.

D from BC · Answer

I'd buy a talking DMM.. Often when I'm probing risky areas, I don't like to take my eyes off the probe. One slip and the probe can short out circuits.

But it's gotta be a sexy female voice.. "Four..hundred..and twenty two point 5 volts." "Four..hundred..and twenty two point 4 volts." "Four..hundred..and twenty two point 2 volts." "Four..hundred..and twenty two point 6 volts." "Four..hundred..and twenty two point 2 volts."

Yah baby!

"Low battery. Please replace battery."

No...no...not now...just one more reading..

"Auto shut off."

Bitch!.....

D from BC

Jim Thompson · Answer

"Faster, faster!" ;-)                                        ...Jim Thompson-- |  James E.Thompson, P.E.                           |    mens     ||  Analog Innovations, Inc.                         |     et      ||  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    ||  Phoenix, Arizona            Voice:(480)460-2350  |             ||  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  ||                  |    1962     |                      America: Land of the Free, Because of the Brave

D from BC · Answer

Now.. now..no taking the DMM to bed..Found example of talking DMMNoo sexy female voice on that page. :(When I turn on the DMM, I want it to say "I'm turned on."Or "Hello darling" would be nice too..Somewhat amusing is the warning on that website...   [This product is not intended for use by the visually impaired.]DMM says:"Four..hundred..and twenty two point 2 volts."Bbbzzzzzzzzzzzzzap!"Zero point zero zero zero volts.""Are you there?""Auto shut off"D from BC

John Doe · Answer

That probably would be far from instantaneous tonal changes providedby a voltage-to-frequency converter, especially if you're usingPlaySound. I don't know about low level sound output in Windows. Or is that just nonsense.

Phil Allison · Answer

"John Dope"** Adding a 1/8 inch connector or similar to a DMM is extremely dangerous !!!!!!DMMs must have  NO user contactable metal parts that link to their insides when in use  -  since the insides can be at  VERY  dangerous potentials.A dedicated, self contained, battery operated device for low voltage circuit use is the only way to go. Then you can use it on DC voltages that are not referenced to ground.Even then, use a plastic case and follow the usual DMM precautions re battery access, leads coming adrift  etc.......    Phil

D from BC · Answer

I think the spoiler would be a slow DMM USB data rate.. Not because of the interface (USB 2 480Mbps) but due to the DMM ADC. There are very fast AD converters available but dunno if they are being implemented in DMMs.

The USB interface and the PC and the software run time would all probably be much much faster.

D from BC

Paul Hovnanian P.E. · Answer

Good point. The audio idea isn't half bad. I have a few meters with continuity test functions that beep. Very handy when I'm working in awkward positions and can't watch the display.

Get a piezoelectric speaker and build the whole contraption inside the DMM case. One more feature: make the audio produce a clear tone proportional to the scale deflection, but buzz for out of range values.

John Doe · Answer

There aren't workarounds? Optoelectronics? Fuse?Thanks. It does some stuff that a multimeter can't do, like an audibleoscilloscope, very limited but very simple and ultra inexpensive.

Including tonal output on a multimeter?

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