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Listening to ultrasonics, a look at Pantellab...

Listening to ultrasonics, a look at Pantellab...

I know some of you may have wondered if I was a bat, well, I have do disappoint ye there, but I really needed a realistic way to test high frequency output from these transducers (of the ultrasonic anti-fouling project).

So, AFAIK electrets, with their very small light diafragm, are still very good at high frequencies, I used to be able to hear that,,,, But HOW high really?

Already was thinking bout the attic where I have some test electrets somewhere from the (ultra low frequency sound heli detector), but hey, I got this free nice small mike with some thing I bought? (cannot remember what it was), and it has this practical clip..

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Main reason I needed to see this was that when sending continuous 2 0kHz and mounting 'the transducer on a large metal 'hull' I heard a tick every few hundred ms.

Turns out to be phase change in the ultrasound when software re-initializes the PIC PWM output hardware, 100 ms tick. Letting it step through the list of frequencies causes a nice clock tick in the audible range.

need to see that, and also HOW MUCH does really come out?

Set to 80 kHz linked list position one, loop on itself:

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Who would have though that mike is still there at 80 kHz, did not test any higher

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So, if you are a bat, and want to meet the media, these mikes are just right for ye.

Reply to
Jan Panteltje
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PS the electret is powered from a CRkweenie 3V battery via a 3k9 resister it does not use a 200 pound motor.

Moving the mike shows a zillion(tm) zeros and maximamas because of all the interfering standing waves in the room. Now 'magine that in water (also known as H2O.

Sorry 'nglish not my lagune.

Hope this helps

Thanks Win for actually showing a circuit diagram of something you made. I see you are assimilating Arduino, interesting.

Reply to
Jan Panteltje

Do a search on hearing bats and you will find a bunch of articles on hetrodyning the bat squeeks down to frequencies you can hear.

Dan

Reply to
dcaster

Which mikes were those, exactly?

--
 Thanks, 
    - Win
Reply to
Winfield Hill

On a sunny day (Mon, 16 Nov 2015 11:30:24 -0800 (PST)) it happened " snipped-for-privacy@krl.org" wrote in :

I know, I think you missed the joke.

Reply to
Jan Panteltje

On a sunny day (16 Nov 2015 18:10:23 -0800) it happened Winfield Hill wrote in :

OK, I did some re-search how I got this one. Wow, that was difficult to find, like I said, it came for free with some other gadget (from ebay):

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I only found it reasoning: Why would anybody add a free mike to anything, must be a recorder or 2 way radio, then searching my ebay emails...

But I am 99.99 % sure that most of these small electrets can do it, if you type 'clip on microphone' in the ebay search window you get one for 1$99 with free shipping, plus a free foam wind shield:

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It won't be "within 3 dB', but physically there is not much to limit the high frequency side, apart from membrane size and wave length, the smaller the thing the better I think, or for the bare-bones solution just ask ebay for electret mike. Now its 10 for 1$99 with free shipping :-)

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Reply to
Jan Panteltje

Thanks, Jan!

--
 Thanks, 
    - Win
Reply to
Winfield Hill

ksid=p2047675.l2557

ay radio,

r 1$99 with free shipping,

high frequency

better I think,

I am using this one for a current project:

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I'm using 3V/2kohm pullup. What is really the right size of that pullup?

Nice bandwidth, for the price :-)

Cheers

Klaus

Reply to
Klaus Kragelund

trksid=p2047675.l2557

way radio,

for 1$99 with free shipping,

e high frequency

he better I think,

Hmm, I meant to say that it looks very much like the one Jan is using

Reply to
Klaus Kragelund

I'm not a bat and I can't easily experiment with ultrasounds or my cat kicks me out of the house:) Anyway, I found the WM61-A (or B) by Panasonic to be a really good capsule for recording; they probably have the highest S/N ratio among reasonably priced fet capsules. Someone also found a way to mod them for getting higher dynamics, though I have no idea if it affects also their bandwidth.

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HTH

Reply to
asdf

Speaking of listening to ultrasonics...

"Beware of ads that use inaudible sound to link your phone, TV, tablet, and PC"

Cross-Device Ad Targeting"

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

On a sunny day (Tue, 17 Nov 2015 04:55:01 -0800 (PST)) it happened Klaus Kragelund wrote in :

On my PC mic input I measured .99 mA with my electret.

Reply to
Jan Panteltje

On a sunny day (Tue, 17 Nov 2015 19:18:28 +0000 (UTC)) it happened asdf wrote in :

Good idea, use the FET as source follower, should be more linear? I had a Tandy / Radioshack electtret mike in the eighties, it had a 1.5 V battery in it, used it in a big hall, got a compliment for the sound. These electret mikes are really good. In those days they were expensive too.

Those things can give half a volt output or so. So 'dynamics' is huge.

Reply to
Jan Panteltje

On a sunny day (Tue, 17 Nov 2015 12:01:12 -0800) it happened Jeff Liebermann wrote in :

I would love them to use ultrasound in their commercials, how easy would it not be to kill those :-)

Reply to
Jan Panteltje

That assumes that they always use the same frequencies, modulation scheme, encoding, data rate, etc. That's probably a good assumption for the first release, but eventually they'll get more complicated and vary everything. Then, you'll need to search for the ultrasonic data broadcast. I suspect your detector or decoder might not be sophisticated enough to differentiate between real ultrasonic broadcasting and jingling keys. I had that problem with a "bat detector" that was equally sensitive to bats as it was to jingling keys and other spurious sources of ultrasonic noise.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

On a sunny day (Tue, 17 Nov 2015 14:21:50 -0800) it happened Jeff Liebermann wrote in :

Yes old squelch detectors monitored the out of band audio, still have some Motorola chip that does that.

But... Somebody in China will read this, guys you can sell a low-pass for between PC and PC speakers...

male male phono in phono out ===| --R ------- ==== | === 10 kHz | lowpass ///

Cost: 15 cent? Sell for a dollar. Huge market.

To prevent PC activating those other devices like pods and droids.

Reply to
Jan Panteltje

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