The electric lighter or spark lighter takes advantage of the so-called piezoelectric effect to generate a discharge and ignite gas. But if you have one already empty and collecting dust in a drawer... why not turn it into a microphone? The very Mehdi Sadaghdar, better known as ElectroBOOM on YouTube, quickly explains the theory, tries a couple of failed designs, and finally arrives at the solution. The final quality of the microphone leaves much to be desired... but it's a project that begs for a chance on your next weekend.
The electric lighter is an extraordinary ally in any kitchen. Just one "click" and the flame comes out. In fact, in many cases it remains useful after its fuel runs out, since its spark is powerful enough to ignite the stove's gas directly. However, these lighters hide a very interesting element. Their ignition system is piezoelectric, so it depends on a quartz crystal or similar material. Now, what does "piezoelectric" mean?
The piezoelectric effect
Steve Mould's explanation is fantastic for understanding the process at a molecular level (beyond the English language), but in relaxed terms, the deformation of the crystal through an impact generates a voltage. If you decide to take apart the piezoelectric ignition of an electric lighter, you'll basically find the crystal inside, a small hammer, and a spring to store energy. When you pull the trigger on the lighter, the spring makes the hammer jump, which in turn strikes the crystal, creating a spark. So... what does a microphone have to do with all this?
https://old.neoteo.com/tu-disco-duro-se-puede-convertir-en-un-microfono/Actually, striking a piezoelectric crystal isn't mandatory. Your own voice is enough for the crystal to vibrate, and thus obtain an audio recording. Of course, the differences in quality and precision between a lighter's crystal and the piezoelectric element of a dedicated microphone are huge, but both behave the same way. The problem is that no matter how hard we try to connect it to a basic microphone input, it won't work without help.
From lighter to microphone
Mehdi Sadaghdar of the ElectroBOOM channel begins by connecting two diodes to protect the device from an accidental hit of the crystal, but the audio recording is null. Luck improves with the use of an oscilloscope, and by completely extracting the crystal. He also added a piece of cardboard to the configuration to record additional vibrations... but his camera remained deaf.
Installing a capacitor didn't help, so he ended up adopting a brute force strategy, and built an amplifier for the microphone. In short, the answer is yes: you can create a microphone from an electric lighter. That it sounds good... that's another story.
