Arduino Wattmeter - Voltage, Current And Power Consumption

Photo of hIOTron

Made by hIOTron / Automotive / IoT

About the project

A device can be utilized to measure the power consumed. This circuit can also act as a Voltmeter and Ammeter to measure voltage and current.

Project info

Difficulty: Moderate

Platforms: Arduino

Estimated time: 1 hour

License: GNU General Public License, version 3 or later (GPL3+)

Items used in this project

Hardware components

Standard Lcd 16x2 White On Blue Standard Lcd 16x2 White On Blue x 1
Arduino Uno - R3 Arduino Uno - R3 x 1
LM 358 Op Amp LM 358 Op Amp x 1
5v 1.5a Linear Voltage Regulator - 7805 To-220 5v 1.5a Linear Voltage Regulator - 7805 To-220 x 1
Single Turn Potentiometer- 10k ohms Single Turn Potentiometer- 10k ohms x 1
Ceramic Disc Capacitor, 0.1 µF Ceramic Disc Capacitor, 0.1 µF x 1
Resistor 10k ohm Resistor 10k ohm x 1
Resistor, 20 kohm Resistor, 20 kohm x 1
Resistor 2.21k ohm Resistor 2.21k ohm x 1
Resistor, 0.22 ohm Resistor, 0.22 ohm x 1
Test load Test load x 1

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Software apps and online services

Arduino IDE Arduino IDE


Building your own meters not only carries down the cost of testing but also provides us room to facilitate the process of testing.

Working of the Project:

From the sensor part, there are two sections that are reliable for measuring voltage and current. For measuring the voltage, a voltage divider circuit is executed using a 10KΩ and a 2.2KΩ Resistor.

With the help of these resistors, you can easily measure voltages up to 24V. These resistors also support us in taking the voltage range to 0V – 5V, which is the normal range on which Arduino works.

In order to measure the current, we have to change the current values to conventional voltage values. As per Ohm’s Law, the voltage drop across a load is proportional to the current. Hence, a small shunt resistor is arranged with respect to the load. By estimating the voltage across this resistor, we can calculate the current.

We have used LM358 Op-Amp in Non-Inverting Amplifier Mode to magnify the values provided to Arduino. The voltage divider network for the feedback control includes a20KΩ Resistor and 1KΩ Resistor. These resistors offer a gain of approximately 21.

After Implementation Arduino Wattmeter

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