I’m asking not specifically about smoke detectors but any device that beeps but does not make any other, non-beeping sounds. Examples include microwaves, the timers on ovens, the fare system on a bus when you give it your fare, the little beepy heart monitor things in hospitals and old-school digital watches. These things beep but they seem to only beep; they do not make any other, non-beeping sounds.
So my question is: how do these things beep? It must be a speaker right (?), and if it is a speaker then why do these devices never make any other sounds other than beeping? (Because presumably speakers have a greater range than just a few beeps.) Or do these devices have specialized speakers that can only make a few sounds? If so, how do these speakers work?
I’m not sure if I articulated this very well but hopefully that makes sense.
Usually it’s not exactly a speaker, but it does involve a controlled moving diaphragm. In a piezoelectric buzzer, a current applied to the diaphragm causes it to oscillate, and the size and shape of the diaphragm determines the tone AFAIK.
It may be theoretically possible to engineer such a device into a rudimentary speaker. I mean, people have done it with Tesla coils and player pianos, so hey, anything is possible?
Interesting. I’ve never heard of a piezoelectric buzzer before. This is the answer I was looking for. Thanks!
You can also make hard drive heads play music. Poor quality music, but music.
Multiple piezoelectric buzzers could probably play a tune if you tune them to individual notes. Not sure how to tune them, but probably cutting them, or putting bluetak on them would alter their note.
How does this work?
A basic speaker is functionally a copper coil next to a permanent magnet. A hard drive head (although I guess more specifically read arm?) is also a copper coil next to a permanent magnet. So if you push an audio signal through the coil, it vibrates and makes sound. It’s missing the diaphram/cone part of the speaker, so it’ll be very tinny.
If you want to make one yourself, get a broken hard drive, and an old pair of headphones, and connect the wires to the coil and play some music.
https://www.instructables.com/Hard-Drive-Speaker-More-Instructive-Version/
Don’t forget floppy drives
Never tried floopy drives, good acoustics?
Have you not seen Flopatron?
Apologies for the YouTube link but I don’t think he posts things anywhere else.
https://www.youtube.com/@PaweZadrozniak
Never seen it before, never been so happy getting rickrolled :D