Help for a 15k-30khz signal generator/Deer chaser

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npapp

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Joined 2006
Hi All, okay this is definitely for Everything else. I want to try my hand a sonic pest chaser to keep deer our of my yard. I see a few commercial offerings that seem very low powered and have questionable results. I need help designing a simple variable signal generator that will operate in the 15-30k range. I will then use that signal to power an T-amp (2020 chip) and a few piezo horns to irritate deer. Or at least that is the plan.

Any thoughts about this actually working. I may hook up this device to a motion sensor and high wattage spot light for some extra impact.

Any help would be greatly appreciated.

Thanks,
Nick
 
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dangus

Member
Joined 2004
Take a look at "Electronic Gadgets for the Evil Genius" by Robert or Bob Iannini. Searching for "evil genius" ebooks may turn up something, if you can't find it at the library or megabookstore. The "Pain Field Property-Protection Guard" is almost exactly what you're building. "More Electronic Gadgets For The Evil Genius" has the "Ultrasonic Phaser Pain-Field Generator", if that book is easier to find.

Also look out for "Build Your Own Laser, Phaser, Ion Ray Gun, & Other Working Space-Age Projects", since there were similar plans in that book. It's out of print, but if there isn't a copy in the library, it can be found on-line too. I made a rat repeller using the swept oscillator, but I simplified the driver part. It didn't appear to bother the rats much, though.
 
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ChrisA

Member
Joined 2008
npapp said:
Hi All, okay this is definitely for Everything else. I want to try my hand a sonic pest chaser to keep deer our of my yard. I see a few commercial offerings that seem very low powered and have questionable results. I need help designing a simple variable signal generator that will operate in the 15-30k range.
Click to expand...

The key here is "variable" The deer will get use to just about any noise. Make it different each time. Maybe even from different speakers.

I'd build the device around a microcontroller and generate the audio waveform in software. This way you can include random sweeps, clicks and pops and if you have two channels of D/A on the uP you can try stereo to simulate a moving sound source.

30K may seem like a high frequency but it's low enough that you can do it completely in software on a five dollar micro controller.

Put a low pass filter in the sound before it hits the amp to kill everything above 30KHz and you will not have to worry about square-ish waves hitting the tweeter.

At the risk of starting a religious war I like the Atmel AVR chips. Yop may be able to build the whole thing using an Atmel "Butterfly" demo board. These sell cheap, well under $20 for the entire computer, LCD screen and all

If you want to go really cheap Atmel makes a "tiny AVR" that sell for about $1, remember that you can output audio through a one bit digital output but controlling the duty cycle and feeding this to an RC filter.

Look here for more
http://en.wikipedia.org/wiki/Atmel_AVR
 
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