| ??? 06/21/06 18:01 Read: times |
#118782 - Detecting high pitch sounds Responding to: ???'s previous message |
Hello Hal,
I think Hollywood loved this story about students getting the upper hand on the teachers by using high pitch sound ring tones. It will blow over because another story will come along Hollywood will put in the forefront. But there is another item more important than misuse of cellular phones in the general public. Detecting high pitch sounds has been around a long time and some of the best are used to detect bats. Searching the Internet reveals some ingenious circuits that allow this to happen. Below is one I thought was pretty good. This area of interest in my opinion is just loaded with opportunity to develop some widget to make somebody a millionaire. Figure if bats can fly in the dark, mate, eat and have fun then there ought to be something mankind could figure out for his needs. Regards, Charles Bannister 
http://pw1.netcom.com/~t-rex/BatDetSch.gif http://pw1.netcom.com/~t-rex/BatDetector.html Build a Simple Bat Detector Tony Messina - Las Vegas, NV |
| Topic | Author | Date |
| High pitched ring tones | 01/01/70 00:00 | |
| LM556 | 01/01/70 00:00 | |
| Download The Ring Tone. | 01/01/70 00:00 | |
| Adding signals with two frequencies | 01/01/70 00:00 | |
| Sure? | 01/01/70 00:00 | |
| Yes, quite sure. | 01/01/70 00:00 | |
| Intermodulation not beat frequencies | 01/01/70 00:00 | |
| Remember piano tuners | 01/01/70 00:00 | |
| A test should tell it | 01/01/70 00:00 | |
| Tuning instruments. | 01/01/70 00:00 | |
| Yes, but... | 01/01/70 00:00 | |
| Mixing 2 ultrasonic frequencys | 01/01/70 00:00 | |
| Cool! | 01/01/70 00:00 | |
| We experimented with the "ionovac" | 01/01/70 00:00 | |
Mixing two rf signals | 01/01/70 00:00 | |
| Adding signals with two frequencies | 01/01/70 00:00 | |
| Don't do that! | 01/01/70 00:00 | |
| I'm with Andy | 01/01/70 00:00 | |
| active noise reduction | 01/01/70 00:00 | |
| Rest your fears | 01/01/70 00:00 | |
| a better idea | 01/01/70 00:00 | |
| Detecting high pitch sounds | 01/01/70 00:00 | |
| No, no, do it the hard way | 01/01/70 00:00 |