How Can You Measure Noisy DC Voltage and Current Accurately?

  • Thread starter Thread starter Jdo300
  • Start date Start date
  • Tags Tags
    Dc Measuring
Click For Summary
To measure noisy DC voltage and current accurately, a high-value resistor and a shunt are proposed for voltage and current measurement, respectively. An RMS to DC converter chip is considered to integrate noise, but it's unclear if these chips can measure the DC component. Jason plans to simplify the setup by focusing on voltage measurement using a resistor divider and a filter capacitor to smooth spikes. He is also concerned about safety when dealing with input voltages up to 1000VDC, particularly regarding resistor selection and capacitor ratings. The discussion highlights the need for careful component choices to ensure accurate and safe measurements in noisy environments.
Jdo300
Messages
548
Reaction score
5
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
 
Last edited by a moderator:
Engineering news on Phys.org
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
 
I used to be an HVAC technician. One time I had a service call in which there was no power to the thermostat. The thermostat did not have power because the fuse in the air handler was blown. The fuse in the air handler was blown because there was a low voltage short. The rubber coating on one of the thermostat wires was chewed off by a rodent. The exposed metal in the thermostat wire was touching the metal cabinet of the air handler. This was a low voltage short. This low voltage...
I am not an electrical engineering student, but a lowly apprentice electrician. I learn both on the job and also take classes for my apprenticeship. I recently wired my first transformer and I understand that the neutral and ground are bonded together in the transformer or in the service. What I don't understand is, if the neutral is a current carrying conductor, which is then bonded to the ground conductor, why does current only flow back to its source and not on the ground path...
While I was rolling out a shielded cable, a though came to my mind - what happens to the current flow in the cable if there came a short between the wire and the shield in both ends of the cable? For simplicity, lets assume a 1-wire copper wire wrapped in an aluminum shield. The wire and the shield has the same cross section area. There are insulating material between them, and in both ends there is a short between them. My first thought, the total resistance of the cable would be reduced...