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

On 15 Mar 2017 14:00:15 GMT, "Peter Heitzer"
<peter.heitzer@rz.uni-regensburg.de> wrote:

>Ray Otwell <ray(no space here)otwell(at)gmail(dot)com> wrote:
>>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.
>
>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.

100K is pretty low.

Joerg wrote:

>> 
> https://www.amazon.com/SOLTEC-HM-102S-Analog-Multimeter-VOLTS/dp/B01M1ETSF9
> 
> Why do these need a 9V battery? At 20k/V input impedance that just 
> doesn't make sense.
> 

** 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