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HP 3400a True RMS Voltmeter? Answered

I have had one of these for the longest time and I really know very little of what it is used for.  It seems to work, but it does not appear to measure like a normal voltmeter, you can't just set it to the 30v range and hold the leads against a 9v battery, you seem to have to pulse it.  Does anyone know about them?  How much are they work because I was thinking of selling it and I have everything for it, the unit, the power cord, test leads, a manual etc.

Any info on it or how it works would be appreciated!



I found one on ebay for £80 including postage. I found another one on an instruments site for $400.


5 years ago

True RMS ( Root Mean Square ) measures the heating energy in a
varying, repeating waveform pulsed DC or AC.

The main feature is the waveform does not have to be a sinusoid it can be an irregular  triangle or square spiked waveform with ringing that comes up in engineering situations..


I think you are essentially trying to measure DC with a meter that is designed to read AC.