Arduino DC Voltmeter with OLED | Measure 0-50V | Complete Wiring & Code
In this Arduino tutorial, I'll show you how to build a precise DC voltmeter that can measure 0-50V using an Arduino and SH1106 OLED display. This DIY digital voltmeter is perfect for battery monitoring, power supply projects, or your electronics workbench.
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COMPONENTS USED:
• Arduino Uno/Nano (any board works)
• SH1106 OLED Display (128x64 I2C)
• 100kΩ Resistor (R1)
• 10kΩ Resistor (R2)
• Breadboard & Jumper Wires
COMPLETE WIRING DETAILS:
VOLTAGE DIVIDER CIRCUIT:
Test Voltage Input (+) → 100kΩ Resistor → Arduino A0 Pin → 10kΩ Resistor → GND
The junction between both resistors connects to A0
SH1106 OLED to ARDUINO:
OLED VCC → Arduino 3.3V
OLED GND → Arduino GND
OLED SCL → Arduino A5 (Uno/Nano)
OLED SDA → Arduino A4 (Uno/Nano)
IMPORTANT: If using Arduino Mega, SCL=21, SDA=20
HOW THE VOLTAGE DIVIDER WORKS:
Arduino reads 0-5V only. The divider scales down input voltage:
Ratio = (R1 + R2)/R2 = (100k + 10k)/10k = 11
Vin = Vout × 11
Example: 5V input → A0 sees 0.454V → displays 5V
Example: 50V input → A0 sees 4.54V → displays 50V
ARDUINO CODE: https://drive.google.com/drive/folder...
REQUIRED LIBRARIES (Install via Library Manager):
• Adafruit SH110X by Adafruit
• Adafruit GFX Library by Adafruit
TROUBLESHOOTING:
If display shows 50V for 5V input → Your resistor ratio is wrong. Check if you used 1kΩ instead of 10kΩ for R2.
If OLED doesn't work → Run I2C scanner. Common addresses: 0x3C or 0x3D
If readings fluctuate → Add capacitor (100nF) from A0 to GND
0:00 - Intro
0:06 - Demo & Overview
0:19 - Components Needed
0:35 - Wiring
0:59 - Arduino Code Walkthrough
1:26 - Testing
1:52 - Outro
QUESTIONS? Drop a comment below. I reply within 24 hours.
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