Accurately measuring noisy DC

[Jdo300]

Hello All,

The final segment of my test circuit includes the ability to measure DC (constant or noisy and pulsed) voltage and current. 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:

http://archive.chipcenter.com/circuitcellar/january00/c10r24.htm

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

Thank you,
Jason O

 

[Jdo300]

Ok,

I think I've decided to simplify the setup by just making a circuit to measure the voltage alone. For this idea, I am thinking about using a simple resistor divider with a small filter cap in parallel with the input to an ADC to smooth out some of the spikes.

Now my question is about any possible concerns that may come up here. I am designing this circuit to take input voltages up to 1000VDC (very overrated for what I am expecting but adding this for a safety margin). At that voltage, is there anything I need to look out for when choosing the right resistors? I know that I at least need to use a filter cap that will handle 1000V.

Thanks,
Jason O

 

[ravenprp]

.

Hello Jason,

Measuring noisy DC can be a challenge, but there are a few options you can consider. One option is to use a low-pass filter to remove any high-frequency noise before measuring the voltage and current. This can be done using a simple RC filter or a more advanced active filter. Another option is to use a digital multimeter with a high resolution and sampling rate to capture the noisy waveform and then use software or a microcontroller to filter and analyze the data.

For accurate voltage measurements, you can use a high-precision voltage reference and an ADC (analog-to-digital converter) to convert the voltage into a digital value. For current measurements, a current-sense amplifier or a shunt resistor can be used in conjunction with an ADC.

As for the RMS to DC converter chip, it can measure both the AC and DC components of a signal. However, keep in mind that these converters have a limited frequency range and may not be suitable for measuring high-frequency noise.

In terms of ICs, you can look into precision op-amps, ADCs, and current-sense amplifiers from reputable manufacturers like Analog Devices, Texas Instruments, and Maxim Integrated. It's also a good idea to consult with an electronics engineer or do some research to find the best IC for your specific application.

I hope this helps and good luck with your project!