PWM Flicker Detector: Hear What You Can't See in LED Lights

Have you ever noticed that the LED screen of a TV or mobile device seems to flicker? It's not an illusion: pulse-width modulation (PWM) is widely used in brightness controls, and many users believe it can cause headaches if implemented incorrectly or if it suffers wear and tear. Instructables user "Faransky" decided to create a device to detect that flicker, and the best way is to turn it into an audio source.

LED technology is everywhere. Simple indicators, remote controls, advertising signs, monitors, TVs, mobile devices, oscilloscopes... the list goes on. It has solved many problems and also brings additional benefits, such as reduced energy consumption.

However, it doesn't seem to be free of compromises. One of them is the flicker linked to pulse-width modulation or PWM. For most users, this is not a problem, and some believe that the side effects of flicker are pure hypochondria, on par with electromagnetic hypersensitivity.

Hear What You Can't See

Now, if from an electronic point of view you have some doubts... nothing stops you from building a detector using very cheap components.

The Instructables user "Faransky" based his design on a PAM8403 audio amplifier (a dollar with free shipping on eBay and potentiometer included), a 5.5V and 80mA solar panel (55 cents on Aliexpress), an 8 Ohm speaker, a lithium battery, a TP4056 module for recharging, and two resistors.

The solar panel serves as the 'input' for the amplifier, which processes the flicker signal and sends it to the speaker. The result varies depending on the frequency and type of light, but it also allows us to detect changes when adjusting the brightness of a screen, and to check the operation of a remote control.

The general recommendation to avoid or minimize flicker is to use brightness at 100 percent, although in other cases (a conventional LED lamp, for example) that is not possible. This accessory does not seek to demonize PWM or anything like it. It's simple electronic curiosity, and a good project for your next weekend, which also won't put a hole in your budget.

Access the tutorial: Click here