Have you ever looked at modern LED lighting and noticed, perhaps on the very edge of your perception, that they seemed to be flickering? Well, that’s because they probably are. As are the LEDs in your computer monitor, or your phone’s screen. Pulse width modulation (PWM) is used extensively with LEDs to provide brightness control, and if it’s not done well, it can lead to headaches and eyestrain.
Looking to quantify just how much flashing light we’re being exposed to, [Faransky] has created a simple little gadget that essentially converts flashing light into an audio tone the human ear can pick up. Those LEDs might be blinking on and off fast enough to fool our eyes, but your ears can hear frequencies much higher than those used in common PWM solutions. In the video after the break, you can see what various LED light sources sound like when using the device.
The electronics here are exceptionally simple. Just connect a small solar panel to an audio amplifier, in this case the PAM8403, and listen to the output. To make it a bit more convenient to use, there’s an internal battery, charger circuit and USB-C port; but you could just as easily run the thing off of a 9 V alkaline if you wanted to build one from what’s already in the parts bin.
Who knows? If you carry this thing around long enough, you might even hear the far less common binary code modulation in action (but probably not).