In this project I have explained how to measure AC current using difference amplifier and pic microcontroller. There are many methods available on internet for measurement of AC current, but there is no method which used difference amplifier and a shunt resistor to measure currents in the range of 10A. In this project, I have designed a AC ammeter using difference amplifier and pic microcontroller.
Voltage drop across shunt resistor is converted into voltage and this voltage is step down with the help of difference amplifier. Negative cycle of sine wave is shifted to positive cycle by applying 5 volt dc offset. After that Built in ADC of PIC16F877A microcontroller is used to measure this analog voltage. Peak value of sine wave is determined with the help of coding and measured peak value is converted back into RMS value of current by multiplying it with 0.707 according to formula of peak and RMS. LCD is interfaced with microcontroller to display current and voltage. You can find complete details about the project of ac current measurement on this blog
Remember always connect high resistors at the input of difference amplifier to avoid reaching high current to the input of microcontroller. Filter capacitors are used at the input to avoid high-frequency components to reach to microcontroller circuits. I hope you like this idea. If you have any question feel free to contact me or comment on this post.
thanks :) Happy coding :)