bat sounds

[The Dong]

K9 Kai Niggemann wrote:
> have you ever tried to record bat sounds? any experiences using a bat detector? anyone know the difference in sound-quality and authenticity of heterodyne and frequency division detectors? do you know any external mics that are less than 2000 EUR that are able to reach up to even 48Khz?

I want to build one at some point, just because there are a lot of bats 
here. I presume the heterodyne ones are old tech, whereas the frequency 
dividers are newer using digital technology, mainly the CD4024 divider 
chip. This is the same chip used in many older and modern Tesoro metal 
detector designs, just as a matter of interest.

To be honest, I reckon it's of little practical use to buy that kit if 
you are savvy enough to build your own and can program micros as a 
bonus. Exactly the same, or better, results could be achieved by making 
up a simple freq. divider circuit (a few at end) then patching in a pic 
micro as a freq. counter using a simple program to give an idea of the 
frequency range your 'target' is producing, or whatever data useful to 
extract. If you only want to hear, omit the pic.

As for mic. I think you need an ultrasonic transducer.

http://home.earthlink.net/~bat-detector/SBD2.html
http://pe2bz.philpem.me.uk/Misc/-%20Animals/-%20Bat/D-203-SimpleBatDetector/BatDetector.html
http://www.openobject.org/objectsinflux/?p=16

After all that, pic chips themselves are perfectly capable of processing 
  such things directly:

http://www.micro-examples.com/public/microex-navig/doc/077-picobat.html

Modify code to your content, two external component parts!
(add LCD, meter, whatever...)