Analog meters: Why do they need a 9V battery?

My trusty old Russky meter died and I can't be sans analog meter for long. Must be cheap and simple because they get dropped, crushed, snatched, whatever. Has anyone used the HM-102S while in the service?

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Why do these need a 9V battery? At 20k/V input impedance that just doesn't make sense.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg
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That meter also measures resistance. It needs the battery so it can source current to measure the resistance. V/A measurements shouldn't need the battery to operate on their own.

Ray Otwell

Reply to
Ray Otwell

Perhaps for reading high (Meg) Ohms.

Reply to
alan.yeager.2013

Yes, but it also needs two AA cells (most meters only need one) and that ought to be enough. This meter requires a whopping three batteries, two AA and one 9V.

If for some reason they use 9V for the highest ohms range that would be ok because it's no big deal when that doesn't work for long.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Possible but still strange because the two AAs should be plenty for a meter with such a sensitive coil in it.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg
[...]

The meter has an Ohm x 10k range; the highest resistance mark on the Ohms scale is 20k: that corresponds to 200 MOhm. With a 9 V battery, the current through a 200 MOhm resistor will be 45 nA ...

HTH

Reinhard

Reply to
Reinhard Zwirner

Oops.

You're entirely right, I just looked and answered without thinking, and without considering that most everyone on here knows FAR more than I do.

RO

Reply to
Gone Postal

Yag...

Sorry for the wrong nym, there.

On Tue, 14 Mar 2017 17:37:55 -0400, Gone Postal and without considering that most everyone on here knows FAR more than

Reply to
Ray Otwell

Some of my previous meters were able to do this but if the 9V battery is only used for the highest resistance range that would be fine. I just want to be sure since I do not want any electronics in the way for DC measurements. I had a analog transistor voltmeter before and in the presence of pulsed RF it was about as fickle as DVMs are. It was so bad that I scrapped the thing.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

If I don't need to measure resistors >100 k, 1.5V is sufficient. Diode test can have a need of higher voltages if one wants to test LEDs also.

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Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de
Reply to
Peter Heitzer

100K is pretty low.
Reply to
krw

** Course it does - when the meter has an " Ohms x 10K" range.

At centre scale, the reading is 200kohms needing about 25uA to get - so requires at least 5v supply.

The meter has no "ohms x 100" range, which could be a problem.

.... Phil

Reply to
Phil Allison

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