We don't have bats that I know of (aside from those in my belfry), but the second reference was certainly interesting. I did not know that rodents and dogs could hear as high as 40 KHz.
If we do have unsuspected bats, they are definitely welcome if they eat skeeters.
There is no limit to the size of the vessel that could be used with this transducer, though size of vessel will certainly affect cleaning efficacy. Whether or not a transistor and oscillator are "good enough" depends entirely on what you regard as "good enough".
You need to finish other things first. Oddly enough, I do too.
I don't need glasses any more so I haven't tried this, but I know they do a great job of cleaning the crud out of my metal watch band. Also, it did a pretty good job cleaning up the orifices on my paint sprayer when I didn't get it cleaned up soon enough. As another poster noted, water, dish soap and a tiny bit of ammonia work great.
I'm currently designing in a PIC to drive a switched mode power supply power transistor, from a battery. The circuit gets booted up when the AA NiMH battery is connected, using a primitive voltage doubler (tiny switch that operates when the case is shut closes and shunts a small cap that was across the battery in series with it), and stays running at 32Khz off the output capacitor, bursting to 20Mhz to run the PSU.
This isn't quite insane.
The fault current is limited by the battery/wires/transistor/inductor to a figure that the can be handled for the time the small cap feeding the micro (and supplying the power transistor with drive) takes to discharge to 1.2V - where even if it's gone through some sort of wacky latchup event, it's going to stop driving current into the base of the transistor.
Also, the load is fixed, and unchanging. If the battery blips out of contact, the load won't drag the voltage below the operating voltage of the PIC for plenty of time to poll the output voltage occasionally, and shutdown to low power mode, where it can sleep happily for a few seconds.
And it can do things that are otherwise hard, like nicely regulating the output current to one of several values, being able to pulse it according to input battery voltage, ...
And worst case, if it gets upset, the user takes out the battery, and replaces. Hopefully this should be rare.
All of this isn't especially hard with 'traditional' chips - but it will certainly take a hell of a lot more space than a 8 pin DFN chip, as well as probably being more expensive.
On Fri, 19 Jan 2007 23:30:13 -0600, with neither quill nor qualm, Don Foreman quickly quoth:
And I didn't know that whales and dolphins heard 150kHz. Shazayam!
By the boatload! A brown bat can eat 3,000 skeeters per night.
BTW, a new pair of dogs moved in next door to me and are getting more vocal by the week. I think they'd like to hear some high frequencies whenever they get to barking and wondered if an audio sig gen would do the trick for about 150 feet. They appear to work from 20-200 Hz with x1, x10, x100, and x1k multipliers. Does anyone know at what frequency these things work?
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- - - - - - - - - - - - - - - - - - Heart Attacks: God's revenge for eating his little animal friends
Cute! Truth be told, I've been thinking about a similar scheme though I hadn't thought of the voltage doubler trick. This would be for a low-current (20 mA) application. I contemplate using a PIC 10F206 in SOT-23. The load would be a single white LED for use in inspecting bores. An SMT inductor would work but I'll probably make one with a ferrite bead since I have those at hand. The appeal to a uC here is that it eliminates the need for a pot, which is not easy to package in something like a little flashlight. The uC can slew brightness up and down using a couple of tiny pushbuttons which are easier to package.
I would be interested in seeing your schematic if you wouldn't mind emailing it to me and if it's not a proprietary circuit someone is paying you to develop. I am just getting started with uC's, have yet to make an actual project using one. It's a new trick for this old dog and it has been kinda slow going thus far.
They typically work at somewhere between 25 and 30 KHz, using cheap piezo tweeters. (The "cheap" isn't meant to be disparaging, they work great!) SPL is on the order of 93 dB at one meter. They're available on line for a couple of bux or used to be. Here we go, $3.95, check out GT1005 at
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The one I tested years ago worked up to 40 KHz.
Don't believe the power rating, that's total program power. These tweeters can take about 10 volts peak-to-zero before they start getting hot.
They're OK at very close range, but I think the remote dog training trick is better done with more power. Think small parabolic reflector and a Hartmann whistle. A Hartmann whistle can be made quite easily on a lathe. Running from shop air, they can produce very intense ultrasound. A 25 KHz Hartmann would be about the size of a 3AG fuse. I figure it in conjunction with a DirecTV dish might produce a SPL of over 120 DB at 150 feet with a beamwidth of about 3 degrees though I've not verified that. I was starting to build it when the dog and its owners moved and saved me the trouble.
I have some design info on Hartmann and Galtier whistles, could scan if you like.
'Fraid not. The tank is 6-1/2" long x 5-3/8" wide by 2-1/2" deep. Dims are appproximate because the sides are tapered, the dims given are about midway.
That'd probably be about 150 watts, probably 3 or 4 transducers. You'd need a thin stainless vessel of suitable dimensions, and some sort of rack -- you don't want a heavy mass just sitting on the bottom of the pan.
Given your talents and resources, it'd probably be easiest to just find or trade for a working unit of appropriate size.
They make much larger ones than would be necessary for this job. The Branson 1620 series has a 16" x 20" x 16" 21-gallon tank, runs 750 watts to 18 transducers.
I'm thinking is there someway that it maybe harmful to the glasses, like making some sort of mistake in time or chemicals.
I can clean them pretty well with an old toothbrush, soap and hot water. I can't get the crude/corrosion in between the frame and the lens though without disassembly. That would be nice to get clean, mostly to prolong their life. Cosmetically I don't really give a toot at this point in my life :)
Oh you have bats. You aren't that far north :) They have had a Bat festival in Iron Mountain, Michigan a few times now. There are several old mine shafts in the UP that are used for hibernation over the winter. See this link and towards the bottom is the heading "4th Annual Great Lakes Bat Festival Summary".
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See also:
Millie Mine Bat Cave
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Ave., North off East A St., Iron Mountain, Michigan
An abandoned mine shaft, with a consistent temperature of 40 degrees. A specially designed cage allows the bats to come and go, but keeps all else out of the shaft! It the second largest known colony of hibernating bats in North America. They leave the mine in late April and return in September, making this the only viewing times. Parking lot, walking path, benches, and informational plaques. FREE!
They do eat skeeters, but don't expect miracles from them.
Cleaning eyeglasses seems to be one of the common uses, along with cleaning jewellry. I would guess plain water with a few drops of liquid dish detergent would be suitable, but it wouldn't hurt to ask your optician what is safe on your lenses with whatever coatings they have.
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