Persistence of Vision (POV) Clock with 51515

Description

Build a Persistence of Vision (POV) Clock with one kit of MINDSTORMS 51515. This model prints the time in the air while rotating real fast! The 51515 POV clock uses only the middle row of the LED matrix on the hub. It times precisely when the lights turn on. This way it can write any number or text in the air. The included program prints a clock, but you can change the program to show any picture or text.

You can see the POV clock best when the lights are slightly dimmed. It is hard to put on video because of the shutter speeds of most video cameras. The pictures below give a more realistic view of how you see the MINDSTORMS POV Clock in reality.

The Python program is made with advanced, undocumented hub properties. I have added inline comments to clarify the code. Feel free to ask for clarification after you downloaded and played with the model.

 

How the 51515 POV Clock works

1. Start the program in the MINDSTORMS app.
2. Set the time with the upper motors. One motor switches between minutes and hours, the other motor sets the value. You can also preset the starting time in the Python code.
3. Tap the hub on its left side to make it start spinning
4. Watch the time!
5. To stop it, hold your hand over the top of the model, where the ultrasonic sensor is

These files are included in the download

• PDF Building instructions, including the wiring!
• Python program for the official LEGO MINDSTORMS app