Hey there!
I'm new here and I like to know where to find the Piezo speaker mention here:
https://www.instructables.com/id/Secret-Knock-Detecting-Door-Lock/
-ikr It's and old project and the writter won't response to any question :confused: -
as I'm not sure which to buy in AliExpress and whenever I ask the seller is this a Piezo speaker? most of them not responding and the other don't know
Also, If you have any suggestion or improvements to the project up there I'd be happy to hear them...