AC and DC Voltage and Current and Resistance Measuring Circuit

[djranganamax]

Can Anybody explain how to design a circuit for measuring " AC and DC Voltage and Current and also Resistance " using analog electronics or using a Micro controller.plz help

And mention or attach the Circuit diagrams and Datasheets that I have to reffer....

plz help me because I have no idea to measure these parameters because I have to design a Multimeter as my undergraduate Project :sad:

 

[Abhishek K]

you can design it....but a dmm is way more costly if you are going to use microcntroller.
DC voltage= use ADC(analog to digital converters.)
AC voltage= use peak detector and then using microcontroller calculate the rms value .(Imax/ root(2)).

---------- Post added at 21:03 ---------- Previous post was at 21:00 ----------

for cicuits, refer Analog Circuit Designs(something like that) by sergio franco (for peak detector )
and MAZIDI for 8051(for interfacing the ADC and programing basics)

 

[FvM]

It's definitely not a good idea to calculate an AC voltage value from a peak measurement, it's effectively the method to introduce maximum error with non-sinusoidal waveforms. No existing multimeter does it this way. You have either rectified value (rectify and average) or true RMS, the latter with higher performance instruments.

I don't know your project assignment, designing a processor circuit may be possibly suggested. Benchtop multimeters mostly are using a microprocessor, but their circuits are rather complex. Classical handheld multimeters have been built around a DVM chip, e.g. Intersil ICL 7106/7107, circuits should be still flowing around the internet. Many retail instruments come with a circuit diagram, so there are plenty of options to gather some ideas. In any way, it's required for a project to understand what you are designing respectively copying, so it can't be avoided to get involved with the analog measurement circuits somewhat deeper.

 

[djranganamax]

Here I want to measure AC and DC Voltage and Current and Resistance and display the values in a LCD or Seven Segment Displays.:sad:

So plz give a help to design a Digital Multimeter......

Plz mention about the specific Analog ICs that I can use for designing the digital multimeter that I can refer the datasheets and can get a Idea:idea:

plz help

 

[Abhishek K]

For RMS value, use a squarer circuit, an integrator, and a square rooting circuit... the first and last can be made using multipliers

 

[nicko-391]

Here I want to measure AC and DC Voltage and Current and Resistance and display the values in a LCD or Seven Segment Displays.:sad:

So plz give a help to design a Digital Multimeter......

Plz mention about the specific Analog ICs that I can use for designing the digital multimeter that I can refer the datasheets and can get a Idea:idea:

plz help

Hve u finished the project?