How do I Calibrate a volt meter?
I have couple cheap volt meters. They don't give show the same numbers. Any ideas how to calibrate? I'm not sure of a cheap and good way. Maybe something that plugs into 120 and then inverts to ...
Forum Discussion
There are multiple ways to calibrate a volt meter depending on the type (AC or DC) and what tools you have
The easiest is to connect in parallel with a meter that is known to be accurate.. (At least for the layman this is the easiest) This works for both AC and DC volt meters by the way.
Another involves a known voltage source. this works best with DC meters.. The problem is there are two different sources that are common.. and I forget the voltage of the most common.
Most common is a standard Carbon Zinc Dry cell battery AA AAA C or D all work well, alas, I no longer have access to the document that gave me the "Fresh cell" voltage.. This must be new, never used.. But the manual for my old VTVM (Vacuum Tube Volt Meter) RCA WV77E was the model as I recall.. Same one I used in college no less.
The proper method involves a variable voltage source, A mercury battery and a galvanometer.. Hou hook them up so the Galvanometer (Measures VERY tiny currents) is in series with the battery and variable source, adjust the variable source so no current flows.. Connect the volt meter to the voltage source (not the battery) and re-center the Galvanometer (Zero current).. THe meter shoudl display the battery's voltage.
Alas, that is Lab Grade Calibration and yes.. I've done that.
The easiest is to connect in parallel with a meter that is known to be accurate.. (At least for the layman this is the easiest) This works for both AC and DC volt meters by the way.
Another involves a known voltage source. this works best with DC meters.. The problem is there are two different sources that are common.. and I forget the voltage of the most common.
Most common is a standard Carbon Zinc Dry cell battery AA AAA C or D all work well, alas, I no longer have access to the document that gave me the "Fresh cell" voltage.. This must be new, never used.. But the manual for my old VTVM (Vacuum Tube Volt Meter) RCA WV77E was the model as I recall.. Same one I used in college no less.
The proper method involves a variable voltage source, A mercury battery and a galvanometer.. Hou hook them up so the Galvanometer (Measures VERY tiny currents) is in series with the battery and variable source, adjust the variable source so no current flows.. Connect the volt meter to the voltage source (not the battery) and re-center the Galvanometer (Zero current).. THe meter shoudl display the battery's voltage.
Alas, that is Lab Grade Calibration and yes.. I've done that.
