Build a Bat Detector
Electronic Gadgets,
Nuts & Volts Magazine (June 2011)
By
Jonathan Berber
This analog project will introduce you to the wonderful world of echolocation.
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Thanks for the Bat Detector circuit! I think I may build this for my kids, so we can see if we have any bats hanging around our yard. When we’re done playing with it, I’ll gift it to my best friend who has a pool in his back yard and gets LOTS of bats EVERY night.
While reading your article, I was struck by something that you said:
“the simplest and most effective ultrasound source was actually one’s mouth. Making a hissing noise… resulted in… surprisingly strong ultrasonic components of the sound. Another technique is to rub two fingers together or slide a fingertip over a sheet of paper held near to the microphone.”
I have a CAT and these are GREAT methods for getting her attention! Hissing is certainly a CAT vocalization. How do you call a cat? “Psssss, Psssss, Psssss, Pssss”, right? Also, rubbing your fingers together is a great way to call a cat who is attempting at all costs to ignore you (as cats are so prone to do).
A quick search of the internet revealed THIS interesting fact:
“The maximum frequency of sound that humans can perceive is approximately 20,000 cycles, or 20 kilohertz, per second. It has been demonstrated that a dog can perceive at least 35,000 cycles, or 35 kilohertz, per second and a cat can even hear as high as 65,000 cycles, or 65 kilohertz, per second.”
The Wikipedia article for cats states that cats can hear up to 79 kHz!!! WOW!
The Wikipedia article for “Bat Detector” states: “Bats emit calls from about 12 kHz to 160 kHz, but the upper frequencies in this range are rapidly absorbed in air”. Later in the article, it says “Research in 2010 observed that frequencies used by bats can be has high as 250kHz”.
So, actually… I may use this device to test a few things around the house ;that I’ve been curious about anyway… Does my CAT make ultrasonic sounds? Does that ultrasonic “rodent repellent” actually DO ANYTHING? etc…
Thanks again for your article!
Posted by Jon Golubiewski on July 27, 2011 at 11:05 AM PST
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