Persistence of vision refers to the optical illusion that occurs when visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye.

Step 1: EQUIPMENTS REQUIRED

1. Arduino Uno/Nano/Mini (1 pc)

2. 12 V DC Motor. (1 pc)

3. Red LED (5 pc)

4. Jumper wire

5. Vero board

6. 9V Battery (1 pc)

7. Battery cap (1 pc)

8. 12 V DC Source

9. Cable tie

10. Nuts & bolts

11. Plastic scale and casing

12. Soldering kit

Step 2: CIRCUIT DIAGRAM

Instead of Arduino UNO ,one can go for Arduino NANO or Arduino mini. LED 1 (as shown in the figure) is connected to Digital pin 2 (D2) of arduino UNO with the help of jumpers . Similarly LED 5 is connected to the Digital pin 6(D6) of Arduino UNO.

Step 3: SOLDERING THE LEDs

The soldering must be neat and clean .

Step 4: FINAL SETUP

A plastic scale is mounted on the shaft of the DC Motor. The 9V battery is fixed to the scale with a cable tie. The Arduino is also fitted to the scale with the help of nuts and cable tie. A plastic casing is attached perpendicular to the scale. The vero board with the 5 LEDs soldered is fixed to the plastic casing with the help of nuts and bolts. The 9V battery is used to power up the Arduino UNO . The 12V source is used to run the DC Motor.

Step 5: WORKING PRINCIPLE

What is POV (Persistence of Vision)?

When a person sees an object, its image remains in the retina of the eye for a time interval of 1/16th of a second. This phenomenon is known as persistence of vision. This phenomenon is used in the LED POV Display to form images. We turn the LEDs on and off in such a way that the different images overlap each other forming letters and characters.Lets take an example of the letter E (in the above figure)to be displayed on the POV Display.

1 2 3 <– Time

1 1 1 <– LED 1

1 0 0 <– LED 2

1 1 1 <– LED 3

1 0 0 <– LED 4

1 1 1 <– LED 5

Each row represents the 5 LEDs we use to make the Arduino POV display and each column is a time interval. Each element in the row represents the state of the LED at that given time.

At time = 1 : LED 1,2,3,4,5 are ON

At time = 2 : LED 1,3,5 are ON

At time = 3 : LED 1,3,5 are ON

This way we can visually see the letter E formed by the LEDs but the time interval would be very small in milliseconds. Due to the short time intervals and the ability of the LEDs to turn ON and OFF very quickly we can see the letter E as all the 3 images merge.

Lets take another example of it. Now we will consider the letter H

1 2 3 <– Time

1 0 1 <– LED 1

1 0 1 <– LED 2

1 1 1 <– LED 3

1 0 1 <– LED 4

1 0 1 <– LED 5

Each row represents the 5 LEDs we use to make the Arduino POV display and each column is a time interval. Each element in the row represents the state of the LED at that given time.

At time = 1 : LED 1,2,3,4,5 are ON

At time = 2 : LED 3 is ON

At time = 3 : LED 1,2,3,4,5 are ON

This way we can visually see the letter H formed by the LEDs but the time interval would be very small in milliseconds. Due to the short time intervals and the ability of the LEDs to turn ON and OFF very quickly we can see the letter H as all the 3 images merge.

This process is also applicable for displaying any numbers.

As the motor is spinning and time passes, each LED moves from one position to the next, so all these images merge together.