A PoE extender generated coil whine precisely at 10 kHz
A PoE extender generated coil whine precisely at 10 kHz
I'm curious about this unusual sound. It seems like a pure tone, almost too precise. I've got PoE extenders all over my home, mostly just for convenience. The noise started in my office and I used a free app to map it. I noticed a sharp spike around 10kHz—probably near the phone mic and DAC. After some digging, I think it might be linked to the power supply or a capacitor resonating at that frequency. The rest of the frequencies are lower, like the usual hum from audio gear, but this one is exactly on target. It's strange how something so specific could pop up, especially with power and data signals operating elsewhere. Any thoughts would be appreciated!
Power supplies transitioning to high-frequency resonance aim to adjust voltage levels by utilizing passive elements beyond the voltage regulator. A switch is integrated to convert the standard 48V PoE output into lower voltages such as 5V or 3V3, commonly found in electronic devices. The switching frequency tends to be very high (100KHz or above), making it inaudible. This behavior could stem from a failing power stage—possibly due to defective capacitors or inductors disrupting the RLC network—or from an inductor that is resonating at a lower harmonic, though this scenario remains uncertain.