This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.
The Finger-Sized Portable Voltmeter operates by measuring an unknown DC voltage and converting it into a digital representation that the microcontroller can process and display. Because standard Arduino board analog pins typically accept a maximum input of 5V, directly connecting voltages up to 24V would damage the hardware. To safely scale down the input, the circuit employs a resistor-based voltage divider network consisting of two resistors in series. This divider scales the incoming voltage down to a proportional value that falls safely within the 0V to 5V range of the microcontroller's analog-to-digital converter (ADC). The Arduino Uno reads this scaled analog voltage through its analog input pin and applies a mathematical scaling factor in software to reconstruct the true input voltage value. Once calculated, the data is transmitted to the compact I2C OLED display using the U8g2 graphics library, updating the screen dynamically to show real-time voltage readings. The entire system is powered by a portable battery or USB source, making the measurement setup completely self-contained and compact.
Why Build This
Provides electrical and computer engineering students with a practical, portable instrument for rapid field testing of DC power supplies and lab prototypes without dragging out benchtop multimeters.
Reinforces core undergraduate circuit theory by implementing a physical resistor divider network and mapping its mathematical transfer function directly into embedded firmware.
Real-World Application
Useful for electrical and electronics engineers, students, and hobbyists for rapid field testing of batteries, DC power sources, and electronic circuits without needing a bulky standard multimeter.
Skills You'll Learn
Voltage divider design
Analog-to-digital conversion
I2C communication protocol
Embedded display integration
Microcontroller firmware scaling
Safety Precautions
Ensure correct polarity connections (positive to power source, negative to GND) to prevent damage to the circuit and microcontroller.
Technology Tags
ARDUINO
OLED DISPLAY
VOLTAGE DIVIDER
C++
ELECTRONICS TESTING
PORTABLE INSTRUMENTS
Frequently Asked Questions
The resistor values in the voltage divider are specifically chosen to scale 0V-24V down to the Arduino's 0V-5V safe ADC limit. Exceeding 24V will output a voltage higher than 5V to the analog pin, potentially damaging the microcontroller.
The OLED display communicates via the I2C protocol, which only requires four wires: VCC, GND, SDA, and SCL connected to the corresponding pins on the Arduino board.
Yes, due to standard component tolerances in the voltage divider resistors, you may need to fine-tune the multiplier coefficient in your Arduino code by comparing your device's reading against a trusted bench multimeter.
Gallery
This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.
0.96 Inch I2C/IIC 4pin OLED Display Module White
Rs. 349.00
Jumper Wire 10 Pin Male To Male 20cm
Rs. 45.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality
Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi
Rs. 139.00
Jumper Wire 10 Pin Male To Female 20cm
Rs. 45.00
