66% or better

Piezoelectric Crystal Speaker for Clock Radio Is Alarmingly Easy to Make

cockadoodledooLet’s face it: most of us have trouble getting out of bed. Many times it’s because the alarm isn’t loud enough to rouse us from our viking dreams. [RimstarOrg]‘s homeowner’s association won’t let him keep a rooster in the backyard, so he fashioned a piezoelectric crystal speaker to pump up the volume.

[RimstarOrg]‘s speaker uses a Rochelle salt crystal strapped to a bean can diaphragm. In his demonstration, he begins by connecting an old clock radio directly to the crystal. This isn’t very loud at all, so he adds a doorbell transformer in reverse. This is louder, but it still won’t get [RimstarOrg] out of bed.

Enter the microwave oven transformer. Now it’s sufficiently loud, though it’s no fire bell alarm. He also demonstrates the speaker using a piezo igniter from one of those long barbecue lighters and a crystal radio earpiece. As always, the video is after the jump. [RimstarOrg] has a lot of relevant linkage in the summary so you can learn how to grow your own Rochelle crystals.

[Read more...]