wattmeter circuit

[compl3x]

we been asked to design a simple electronic wattmeter on the breadboard which measures true power, apparent pwer, rms current,rms voltage & power factor. im lookin for a simple schematic of the wattmeter circuit....to be used, this has to measure current and voltage separately and a code will be written on matlab to achieve the measurent of power, serial comms or an LCD will be used to display the measured values, microcontroller used will be the ATMega16!

[arthur92710]

Atmel actual has a "Application note" for a power/energy meter. The one they made is for 220v and 10A, but they say it can be adjusted for any voltage/current.

Its a very good document! They show all formulas and explain every part in detail.

Actualy I have asked a similar question here

Here are the links:
Pic based power meter It could be fixed for an avr.
Simple digital AC wattmeter
1v/1000w
Optoisolators compute watts and volt-amperes

[compl3x]

thanks a million arthur!

[arthur92710]

No problem.

But their is a much simpler way to do it. (It might have some problems)
If you have a load like a light bulb, take a small value resistor (1 or .1 ohm) and put it between the bulb and the nutral wire. Then measure the voltage accross the resistor.

Here is a simulation video. Just give it a few seconds to load.

[arthur92710]

Well the problem with the simpler resister circuit is that its not linear. I tried to fix it but cant. One of the other guys can help with that.