RayPong

Top video: v1. Bottom video: v2

Club member, Pak, is on a mission to create a “let detector” AKA a notifier that a ball has hit the net on a serve. Please talk to Pak for more information and to see it in action! I hope this becomes an Instructable or other type of DIY project for both clubs and professionals.

Information from Pak:

Process

1. Identifying a sensor that senses “minute” vibrations of a table tennis net. After some considerations, I purchased this cheap accelerometer (ADXL335 3-Axis) from Amazon which claimed to have high sensitivity. I stay away from 6-axis accelerometers.
2. Identifying a microcontroller that has programmable analog components to interface with the “sensor.” This is easy since I am familiar with the Cypress Semiconductor PSoC. PSoC is a microcontroller with programmable analog components. In particular, I need a PSoC which has at least two analog to digital converters (ADC).

At this moment, I am using a Cypress CY3210 Evaluation Board to prototype the “let detector.” The main control loop is written in the “C” programming language. It took me about half a day to get everything working.

I coded everything from fresh and nothing is lifted off any websites.

This project was inspired by the introduction of TTR in ITTF world cup April 2025, and VAR in soccer.

What happens

Currently, when my “let detector” senses vibration of the net, it flashes an LED. The accelerometer needs to be hung off the net which probably is a violation of the official table tennis rules.

The 2nd version now has sensitivity adjustment.

Future

I have seen table tennis competition events which use microphones (sound) to assist the umpire to detect a “let.” Let’s see if I can also incorporate sound as a mean to detect a “let” in my “let detector” version 2.0.