audioguru2
- Apr 6, 2004
- 12,026
- Joined
- Apr 6, 2004
- Messages
- 12,026
Nobody has talked about this project for a while:
http://www.electronics-lab.com/projects/misc/002/index.html
It has very high gain when the piezo sounder is used as a microphone and only a little filtering. I wonder how well it works.
Recently my daughter brought me a Keys Finder that she got on sale for 6 bucks.
"Dad, can you fix this? It goes off all the time."
It doesn't always go off. I can scream at it and jump on it and it is quiet. Loud clapping doesn't do anything. But when my daughter and wifey talk quietly or when the TV or a radio is on, it goes beeping in a Morse code for 5 times, rests for a moment then goes off again and again.
Inside it has two button battery cells, a red LED, two surface-mount resistors, a 1" piezo sounder and a black blob for its IC.
I don't think I can fix it. I found out that if I whistle at exactly one octave below its high beep frequency then I can make it beep from far away. I think our project will perform the same.
View attachment 38154
http://www.electronics-lab.com/projects/misc/002/index.html
It has very high gain when the piezo sounder is used as a microphone and only a little filtering. I wonder how well it works.
Recently my daughter brought me a Keys Finder that she got on sale for 6 bucks.
"Dad, can you fix this? It goes off all the time."
It doesn't always go off. I can scream at it and jump on it and it is quiet. Loud clapping doesn't do anything. But when my daughter and wifey talk quietly or when the TV or a radio is on, it goes beeping in a Morse code for 5 times, rests for a moment then goes off again and again.
Inside it has two button battery cells, a red LED, two surface-mount resistors, a 1" piezo sounder and a black blob for its IC.
I don't think I can fix it. I found out that if I whistle at exactly one octave below its high beep frequency then I can make it beep from far away. I think our project will perform the same.
View attachment 38154
