Quote:
Originally Posted by timmy
Well there is a difference in meters I have a cheapy meter from sears looks just like the one mentioned in the previous few posts and on one pin I checked was 288 v but with the cheapy meter it showed 203 v that’s a 15 volt difference wow I have to check all voltages again.
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Uhmmm.... You know the difference between 203, & 288 is not 15......
Also, Impedance is AC resistance.
You can calculate the DC resistance, or see it's effect on a circuit under test
with a simple test. Take a known voltage source like a good 9V battery,
connect 2 - 1meg-ohm resistors in series, measure the voltage across each
with your meter, and see what the two numbers add up to. Too far away
from 9V and you know your accuracy is going away. Do the same test
with 10Meg-Ohm resistors etc. Up or down to know at what point you
will begin to get poor readings.....
EX. With the 10Meg-Ohm resistors you measure 3.5V across each, in this
case adding up to 7V. On a known good 9V source. Your meter is loading
the circuit and effecting the accuracy of your work.
This was a bigger problem with needle type meters that were 20K-Ohm/Volt.
resistance loading on a DC scale. Most had it printed on the meter face so
you knew when to suspect meter loading. Most Digital meters are very high
input resistance to DC.
.