A Portable Flickering Detector for Any PWM-Operated Light Source
This DIY device lets you actually hear a light’s frequency.
When you look at your computer monitor or overhead lighting, it may appear to be a solid color, but in reality there is a very good chance that it’s flicking many times per second. This flicking is normally imperceptible to normal human vision — and can be used on purpose to vary perceived light intensity via PWM (pulse width modulation). This may, however, cause negative effects like headaches and eyestrain. The good news is that there is a wide variation in how light is produced, and the Portable Light Flickering Detector lets you actually hear a light’s frequency.
The detector’s design is quite simple, with a portable solar cell hooked up to an audio amplifier and powered by a Li-ion battery. The amplifier powers a small speaker inside the unit, causing it to buzz annoyingly along with the light’s frequency. A headphones jack is included, as well as a potentiometer that features a switch to vary the volume and turn it off as needed.
The video below is enlightening, demonstrating a wide variation in frequencies between devices. Even two seemingly identical overhead LED lights are shown exhibit a different frequency, so you never know what you’ll find. It’s certainly something to consider next time you’re in the market for a new monitor or other light source, especially if you’re prone to eyestrain.