ageedizzleDo smoke detectors have little speakers inside them? If yes, would it be possible to hack them to play a little jingle?
Fermionlabdarna.com/…/understanding-piezo-buzzers-how-th…
They use piezo buzzers which work differently to most speakers. I would guess that the units used in smoke alarms and microwaves generally have integrated drivers that only operate at a single frequency. However, it is possible to drive piezo discs at different frequencies. Their ouput will always approximate a sound wave though, so don’t expect to be able to use them like a normal electrodynamic/ voice coil speaker to play arbitrary sounds.
ChaoticNeutralCzechPiezo buzzers have a resonant frequency they’re strongest at. Two-pin piezo disks need driving at the desired frequency. Three-pin provide a phase-shifted feedback to the driving transistor to keep oscillating at the resonant frequency. Some include that whole circuit inside their housing so they have just 2 pins but those are for DC power, only the volume can be somewhat adjusted by changing the input voltage.
The only ones I’ve ever used myself area is the DC variety. Apply power: beeeeep; stop applying power: <sound stops>
I don’t know why idea are more commonly used in consumer electronics.