AC Voltmeter Using Arduino

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Introduction: AC Voltmeter Using Arduino

About: Nothing just a tech enthusiast and by degree an Electrical Engineer

This is a simple circuit to ascertain the AC voltage using the Arduino UNO without any AC voltmeter!! ENJOY!!

Step 1: COMPONENTS REQUIRED

Read explanation for knowing each ones use...

1) Step-downTransformer (12V or 6V), i have used 6V one

2) Resistor (2P- 1K ohm as I used 6V Tx, for 12V its 1K and 4.7K )

3) Diode(1N4007)

4)Zener Diode (5V)

5)Capacitor (1uF preferably or else 10uF more time to discharge charge!!)

6) Adruino UNO or any obviously and some jumpers(2)

All this are the components that are required to draw the project into existence...

Step 2: Circuit Diagram and Explanation

Can you see that circuit?? OHHH... yes nothing in it

1)Step-down transformer(220V to 6V AC) but the arduino can't take AC voltage to read that also 6V

2)Lets get the 6V down to 5V operating voltage of Arduino so that it can measure or read, so voltage divider using 2 1k resistor so it comes to 3V AC(approximately)

3) To get a DC we have used a diode as a half wave rectifier

4)Now 5V DC has to be maintained not more than that so we have used a capacitor to stabilize the voltage and a zenver diode as voltage regulator that keeps 5V at terminals always!!

So, now the circuit part is done now we will take out jumpers from terminals shown in circuit diagram(i.e. across zener diode) and put the jumpers(+) to A0 analog pin of Arduino and (-) to GND of Arduino.

If you dont know the anode and cathode of diode refer to internet its easy! silver side cathode(1N4007) AND black side cathode(zener diode).

Step 3: Arduino and Code!

Arduino's pin A0 and Gnd as been used to analyse the coming voltage with respect to AC mains...

5V input at A0 pin refers to 1023 bit value of arduino...

So, 220V AC (r.m.s.)= 311V(peak) corresponds to 1023bit

1bit correspond to = 311/1023 , Thus we have taken, b=analogRead(A0) and ac voltage=a=(b*311/1023)

Now the voltage that we get is peak voltage to get r.m.s. we divided peak/sqrt(2).

BUT, if we just say serial print Arduino will continuously plot voltage so we have made a program to show output only if the input changes.

Thanks for reading this small but useful project if you dont have ac voltmeter near you.

I will come up with IoT projects from the next one.

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    3 Questions

    We don't no house voltage what we can do ??

    I have a transformer that I want to repurpose, but its output is 16v AC.
    What would be the sizes of the resistors I have to use to match it? Any
    other change that I need to be aware of? Thanks in advance.

    If the transformer got a center tapping you can get 8V AC that will be better, in case you don't have it do one thing. Use the same logic i.e. voltage divider. TO DIVIDE THE 16V TO approx. 5V AND 10V using 2-3k Ohm resistor. But as the power will be slightly more so recommend to use higher power resistors or else try once if it gets disrupted then try the recommended. BE SAFE THOUGH!! CAUTIOUS AS IT'S AC.

    how many amperes does this circuit can handle?

    Hello, its a voltmeter so as described, it is made up of Arduino thus it can handle 5V i.e. 230V corresponding to 5V by the use of transformer, zener diode and capacitor. Lastly, a voltmeter is a galvanometer with high resistor in series so that negligible current flows through it. Thus this circuit is for 5V, can't say the current rating as current is not a factor here. Now don't go for 440V !! for household voltage and lower voltages its safe. No current actually goes from the circuit to arduino just the potential is measured.

    7 Comments

    what is the current capacity of this voltmeter?

    2 replies

    Hello, its a voltmeter so as described, it is made up of Arduino thus it can handle 5V i.e. 230V corresponding to 5V by the use of transformer, zener diode and capacitor. Lastly, a voltmeter is a galvanometer with high resistor in series so that negligible current flows through it. Thus this circuit is for 5V, can't say the current rating as current is not a factor here. Now don't go for 440V !! for household voltage and lower voltages its safe. No current actually goes from the circuit to arduino just the potential is measured.

    +1

    People ask the darnest things ;-)

    Hey man nice work... I tried to do it... But the output is working only for some period of time ... After few hours the output put is not working values are not matching with the multimeter ...

    1 reply

    May be the capacitor you are using is getting depleted, means it isn't storing charge as usual. So change it as well as the zener diode. Check it and let me know.