Accurately measuring the voltage of an arbatrary waveforum

Thread Starter


Joined Oct 14, 2007
Hello All,

I am designing a circuit board that has the capability to measure the voltage and current across/through some test coils that I am playing with. The output that I am expecting to measure is essentually pulsed DC with lots of hash.

I'm trying to come up with an elegant solution that will give me decently accurate measurements. What I have thought of so far is to use a high value resistor to measure the voltage and a shunt to measure current, but i'm not sure what kind of IC to use to accurately get the votlage and current values.

Most of the stuff I play with generates lots of funny waveforms that aren't anywhere near clean so I'm wondering if I whould use an RMS to DC converter chip to integrate all the noisy stuff and then feed that into a DAC. But if I use one of those chips, do they also measure the DC component as well? I've never really delved into this area so I'm not sure what IC or apparach would be best. So far, the best resource I have found is this link here:

But there are so many options to choose from. Would anyone happen to have some advice for me on this?

Thank you,
Jason O


Joined Apr 20, 2004
There are several true-RMS converter chips available. Good meter have them. Your application might be a bit much for a meter, though. If your budget will stand it, think about a good digital oscilloscope. That would let you capture the waveforms over a period of time and play it pack. On-screen cursors let you display the voltages of the hash and the DC pulse.

Another way out is to get an A to D device like the Dataq DI-720. It has some funnies in operation unless all unused inputs are grounded, but lets you take in the complex waveform and examine it at leisure.

These are both multiple-thousand dollar solutions, sad to say.