Ac voltage measurement using Arduino: In this article, we will see how to measure ac voltage using arduino and how to design ac voltage detector circuit using arduino uno r3 and how to design alternating voltage measurement sensor using a very simple technique and at the end, we will see how to write ac voltage / potential measurement code in arduino programming. So it will be a simple arduino based ac voltmeter which can measure 220 volt very easily and without any need of external sensor. I will start writing articles from this week on how to measure ac current , ac power, power factor using Arduino and I have already written a articles on all these topics using pic microcontroller. But on the request of users,I will be also writing these articles using Arduino. Check following articles which are based on pic microcontroller projects.
So now lets see how to measure ac voltage using Arduino and how to design ac voltage sensor using Arduino and I recommend you to check arduino tutorials and Arduino projects first, if you are a beginner in Arduino programming.
Followings are the main components required for the design of ac voltage detector with Arduino:
To measure ac voltage with the help of Arduino, first of all you need to design alternating current voltage measurement sensor. First example if you want to measure voltage of magnitude 220 volt AC. you need to step down this voltage first. Because Arduino has built in ADC channels and maximum voltage that Arduino analog channel can measure is 5 volt. So we can not measure voltage greater than 5 volt with the help of Arduino directly. you should also know how to measure analog voltage with the help of Arduino or how to use analog channel of Arduino. if you don’t know, check this article on how to measure analog voltage with Arduino.
It will give you an idea on how to use analog channel of Arduino. Because it is a first step towards designing ac voltage sensor with Arduino and ac voltage detector meter with Arduino. As I have explained earlier, in this project I have used difference amplifier to step down voltage from 220 volt AC to less than 3.3 volt AC. Because built in ADC of Arduino can not measure voltage more than 5 volt. So we need to find a way to step down voltage. There are many other methods to step down voltage like potential transformer or step down transformer which is a expensive method for low cost applications. Voltage divider method, it is a least expensive method for this purpose. But it has disadvantage of less voltage range and more power consumption. So we can not use it critical power applications.
So I have come up with another method using operational amplifier. I have use operational amplifier for a step down purpose. Operational amplifier is used a difference amplifier. By adjusting the gain of operational amplifier, we step down the voltage to less than 3.3 volt. I have explained all the theory and working of difference amplifier for to step down ac voltage in separate article on ac voltage measurement using pic microcontroller. I recommend you to check it, if you want to get more understanding about this method. Circuit diagram of difference amplifier is given below:
Input to difference amplifier is 220 volt ac and output of difference amplifier is less than 3.3 volt. I have also added 5 volt dc to ac to convert negative cycle into positive cycle. Because Arduino can not measure negative voltage directly. Again refer to the article on ac voltage measurement using pic microcontroller for more understanding and why I added 5 volt dc level to the circuit. Output of this circuit is fed to analog channel of Arduino which measures this voltage and after performing some calculations displays measured voltage value on LCD.
Circuit diagram of ac voltage measurement using Arduino is given below:
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