Anti-mosquito

I remember hearing multiple story lines on how this type of a device is supposed to work and why it fails. The silly theories I heard I won't post. The plausible theory I heard on how an ultra-sonic burst will repel some insects was that it mimicked the echo locating sound of a bat. I've seen this demonstrated with a wine glass and the wine bottles cork affecting a group of moths. The cork rubbed the rim of the glass and the swarm of moths around a nearby light dropped precipitously in flight. The guy doing this demonstration pointed out that this will only work as an infrequent trick. In other words, if the moths hear something that sounds like a bat but a bat never fly's through their airspace then its not a bat. Sure enough after repeated use of the cork the moths just ignored the chirp.

What I do remember with humanity's perennial fight against mosquitoes is that they track us by the slightly higher amount of carbon dioxide we put in the air, particularly CO2 without soot particles. This is why a simple campfire and/or enough candles (with or without citronella) masks our tracking scent.

Oh, one last comment on the circuit. Most speakers will not effectively translate ultrasonic electric signals to ultrasonic sound waves. I believe that one can use a piezo based tweeter to do this but a 10 inch Cerwin Vega woofer will do nothing at these frequencies.