Author Topic: How to make a simple voltage measurement device  (Read 734 times)

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Offline houkensjtu

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How to make a simple voltage measurement device
« on: July 29, 2015, 12:56:26 pm »
Hi there!
I want to make a simple voltage measurement device myself which can:
1. Measure a DC voltage range from 100-200V
2. Have reasonable accuracy, say error less than 0.1%

I thought a cheap multimeter may give me some idea so I tore down my multimeter, I expected that there would be an AD converter like chip, but the only thing I found is a single central chip(most likely a microcontroller) on the board.(you can find my photos in the attachment)

Here is my question:

1. What is the standard way to measure voltage in digital multimeter?
2. How should I deal with the high DC voltage (because usually microcontroller can't afford that high voltage input)
3. Is it better to use a seperate AD converter than using microcontroller's build-in AD converter?

Thank you all!
 

Offline Richard Crowley

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Re: How to make a simple voltage measurement device
« Reply #1 on: July 29, 2015, 01:57:11 pm »
1. What is the standard way to measure voltage in digital multimeter?
Most lower-end DMMs have specialty chip like Intersil ICL7106. It handles everything from measurement to display-driving.

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2. How should I deal with the high DC voltage (because usually microcontroller can't afford that high voltage input)
Simple voltage divider. Add protection clamps (diodes, etc.) if there is danger of over-voltage.

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3. Is it better to use a seperate AD converter than using microcontroller's build-in AD converter?
Does the microcontroller's built-in AD converter meet your requirements?
 


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