Best Bat Detector

August 1, 2007 3:24 AM

I'd like to listen to the bats in my local park. What kind of detector should I get?

I have rudimentary soldering skills, but was impressed by the home made bat detector featured in Make. Should I go for that entirely DIY solution, order a pre-compiled kit, or just pay up for an assembled detector? I don't really know what advanced features I'm looking for, but would like to be able to distinguish Pipistrelles, noctules and Daubenton's bats, and would ideally want a detector with a regular headphone jack.

posted by roofus to Pets & Animals (4 answers total)

How would you rate your desire to learn electronics vs. your desire to hear bats? If you're excited about building stuff for yourself, the circuit described in the page linked from Make: doesn't look too difficult to build up and could be a pretty fun intro project. However, it sounds like there could be some amount of fine-tuning involved depending on your transciever, so it's probably not a project you want to get into if the idea of fiddling with it doesn't excite you.

I say go for the scratch build (or order his kit and assemble that), but then I love this kind of thing.
posted by Alterscape at 4:12 AM on August 1, 2007

I can't find the one I built right now but the DIY one sounds much better. He's not kidding about analog vs. digital. On mine I have to tune a little knob to the frequency to down convert which means I loose everything on the other frequencies, and bats aren't monotone so it's like having half the picture. I'd go with "frequency division" next time and a few ready made kits appear to be out there for that.

I'd love to hear from someone with experience on both types though.
posted by jwells at 5:24 AM on August 1, 2007

No experience, but this page explains the various types.

Both hetrodyne and frequency division types seem bad to me. I think a better (but more complex) way would be a reverse of the technique players use to give audio from a CD when FastForward is engaged, ie have a microcontroller with A/D record 0.1 seconds of bat ultrasound sound into a buffer, play it back at 25% speed for us, then 0.1s before it's finished playing, start recording the next 0.1s ultrasound sample. It seems that way you'd get more informative sound than just digital beeps, and you wouldn't need to tune for frequency (missing the rest). The downside is that you're sampling the bat only 25% of the time in order to make the playback realtime, but since you're sampling a few times a second, it should give a good picture.
posted by -harlequin- at 6:53 AM on August 1, 2007

If it helps, the first few electronics projects I tried were an incredible mess. I was overheating stuff when soldering, making a mess, making amateur mistakes, pulling my hair out, etc. I figure your first 5 or so projects will be purely learning experiences and you may not have a well functioning (or at all functioning) toy when youre done. If youre willing to chance this, go the DIY route. If you just want a bat detector go ahead and buy one.
posted by damn dirty ape at 7:18 AM on August 1, 2007