My project is a “breathing” white 12v LED strip controlled by an esp32 on a dev board, and switched with an IFLZ44N mosfet.
In my video you can see it working but also hear the power supply complaining.
I’m using the LEDC Arduino library which allows me to select the frequency and resolution for PWM.
If I set the frequency too low the whine is extreme, but at this setting it’s the best I’ve been able to achieve, which is about 9000Hz. Unfortunately you can still hear the sound from across the room!
It is a cheapo solid state power supply that claims it can output 12v up to 25A. I tried my desktop supply and it emits some whine too, so I don’t think replacing the power will totally fix this.
Is there a technique for tuning the frequency or even just masking it somehow?
Thanks for typing this up! This helps me understand a lot more about what is going on.
I may have purchased too large of cap for the first try: 470uF. I bought it online so still waiting for arrival. I’ll get some in the 40uF to 200uF range for more testing