Is it true that older residential smoke alarms tended to buzz, whereas modern ones tend to beep?
Yes. Older smoke alarms used what’s called an electromechanical alarm horn, Often called squealer horn by us, And newer alarms, and what we have today use piezoelectric horns.
Yes, here is a video:
they sound really weird
When I was very little, I lived in a house with an older buzzing smoke alarm. I was terrified of it. When I moved to a new house that had a modern beeping smoke alarm it was a relief. I wasn’t as terrified of it, as I was of the buzzing one.
Sort of reminds me of a 4051 at my junior high school.
Why did they change just found a cheaper way
I imagine it is cheaper, but also beeping is easier to be heard, and the vibrations won’t increase the the likeliness of failure. It probably also has less current draw.
Yeah, the piezo alarms use less current than the “squealer” alarms, This allows the battery in battery-powered alarms to last longer, especially when the unit is in alarm state.
It’s just like how Piezo/Electronic NAs have less current draw than EM models/bells.