If you are following my PCB actuator projects you have probably noticed that they beep when placed near a magnet. This is because I am driving them with a frequency that is in the hearing range. It sounds like a very weak buzzer. This is because a speaker is basically made from a coil that actuates a magnet to move air.
This is where my PCB Speaker idea came from. With some modifications, I managed to play music from printed traces! It is very simple and works just like any other speaker.
Its main components are the magnet and a coil, in this case a flexible printed traces. The vibrations created from the coil pushes the surrounding air to create sound waves. To measure how loud my PCB Speaker is I am using an spectrum analyzer app. A maximum 70db level was reached!
I have also tested the PCB with plastic cup acting as the diaphragm. This amplified the sound even louder. I also managed to make it work with a 1.6mm rigid PCB, by attaching the magnet to the diaphragm.