Arduino POV Clock: Build a Persistance‑of‑Vision LED Display

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Arduino IDE (v2.x)

About This Project

This guide walks you through building a compact Persistance‑of‑Vision (POV) clock using an Arduino Nano, 19 LEDs, a Hall‑effect sensor, and a DC motor. The result is a rotating LED display that creates a floating, time‑displaying image when viewed from the side.

The project uses a lithium‑ion battery coupled with a step‑up converter for a lightweight, portable power supply. With 19 LEDs arranged in a single‑column 19×1 matrix, the clock can display numbers, symbols, or custom patterns.

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Step 1: Required Materials

In addition to the components listed in the table above, you’ll need the following items:

• 19 LEDs (3 mm, green) – arranged in a 19×1 row
• 220 Ω resistor for each LED (except red LEDs)
• 330 Ω resistor for red LEDs if you use any
• DC motor (12 V or 24 V, 500 rpm‑800 rpm)
• Magnets for Hall‑effect sensor alignment
• Perfboard or a veroboard for soldering
• Wires, solder, and a small screwdriver
• Lithium‑ion battery and step‑up converter (5 V output)

Step 2: Circuit Diagram

The diagram shows the Arduino Nano connected to the LED row through current‑limiting resistors. All cathodes are tied to a common ground line. The Hall‑effect sensor receives a 5 V logic signal and outputs a pulse when a magnet passes by.

Download PDF Circuit Diagram

Step 3: Assemble the Motor Base Board

Choose a stable base – a wooden plank, cardboard, or any flat surface will work. Drill a central hole that snugly fits the motor shaft and secure it with a screw to allow free rotation.

Step 4: Assemble the Circuit

Mount the 19 LEDs in a straight line on the perfboard. Attach the appropriate resistor to each anode and solder them in place. Connect all cathodes to a single ground trace. Once assembled, test each LED with a 3.7 V coin cell to confirm functionality.

Mount the Arduino Nano on the board using two female header strips for a secure connection.

Step 5: Connect LEDs to Arduino

Wire each resistor’s free end to a digital pin on the Arduino Nano (e.g., D2–D20). Use a single jumper wire to connect all LED cathodes to the GND pin. This configuration allows the Arduino to control each LED individually.

Step 6: Mount the Propeller in Motor

Attach the LED row to the motor shaft, ensuring it is centered and balanced. Place a magnet on the motor’s side so the Hall‑effect sensor on the Arduino can detect each rotation. This pulse triggers the LED pattern to refresh.

Step 7: Programming

Download the Arduino sketch that controls the POV clock and upload it to your Nano:

• Pov_Pendulam_Clock.ino

The code uses the Hall‑effect sensor’s interrupt to time the LED activation, creating a smooth, floating clock display.

Step 8: Testing

Once powered, the rotating LED row should form a clear, persisting image of the time. Adjust the motor speed if the display flickers or appears blurry. For best results, keep the viewing distance between 30 cm and 60 cm.

Code

• Pov_Pendulam_Clock.ino

Schematics