ttims@watdcsu.UUCP (11/17/87)
I am interested in owning an ultrasonic cleaner. I figure it's
got to be the ultimate way to clean bike parts. A cleaner with
a reasonable tank size (3 to 5 litres) is quite expensive. (500
dollars Canadian.)
Does anyone have any experience or knowledge about them? I would
be willing to build one from scratch if it was easy enough. Anyone
knw how to build one? Does anyone know what I should look for if
I buy one?
Tracy Tims
ttims@dcsu.waterloo.edu
{ihnp4,watmath}!watdcsu!ttimslarry@kitty.UUCP (Larry Lippman) (11/18/87)
In article <4125@watdcsu.waterloo.edu>, ttims@watdcsu.waterloo.edu (Tracy Tims) writes: > I am interested in owning an ultrasonic cleaner. I figure it's > got to be the ultimate way to clean bike parts. A cleaner with > a reasonable tank size (3 to 5 litres) is quite expensive. > Does anyone have any experience or knowledge about them? I would > be willing to build one from scratch if it was easy enough. Anyone > knw how to build one? Does anyone know what I should look for if I buy one? Two major vendors of ultrasonic cleaners are Branson and Sonicor; their prices are roughly comparable. Two common sizes are 4 liters and 10 liters. 4-liter units can be had for around $ 300.00 (wholesale), and 10-liter units can be had for around $ 600.00. Such cleaners are also available with heaters at an additional cost of $ 75.00 to $ 100.00. For your application a heated unit would probably be better. Cleaning and degreasing detergents specially formulated for use in ultrasonic cleaners are available. My organization has a couple of ultrasonic cleaners, and they are both made by Branson - which also sells appropriate detergents. I do not believe it is practicable for you to consider building such a unit yourself. <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|utzoo|uunet}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
gene@cooper.cooper.EDU (Gene from EK Enterprises) (11/18/87)
in article <4125@watdcsu.waterloo.edu>, ttims@watdcsu.waterloo.edu (Tracy Tims) says: > A cleaner with a reasonable tank size (3 to 5 litres) is quite expensive. > > Does anyone have any experience or knowledge about them? I would > be willing to build one from scratch if it was easy enough. Anyone > knw how to build one? Well, if you can get a relatively high powered ultrasonic transducer, it might be worthwhile to actually build one. As for the case/tank, you might even try your bathtub in a pinch! Personally, I'd try a dedicated tank approach. As for *how* they work, it's what's called cavitation of water. Under ultrasonic stimulus, water molecules "bubble" in sync with ultrasonic waves. It's not the sound that lifts off dirt and grime, but the bubbles' action. (Talk about "scrubbing bubbles", literally!) Anyway, all that's needed is a source of ultrasonic energy. A common audio tweeter (piezoelectric) is available from Radio Shack. It costs $5, handles 75W of power, and is (more or less) easy to waterproof. Although I've never tried this, it *MIGHT* be possible just to enclose the bugger in a Baggie and tie the open end tightly. If you're more adventurous, you might try to just leave the beastie open, and dangle it underwater. (Pure water is a great insulator (k=78.0), but enough impurity turns it into a great conductor, too.) As for the ultrasonic driver, a 555 timer works well directly. From a 9V battery, you'll get exactly 9V across the piezo's terminals. HOWEVER, (!) you can boost that to over 75V terminal voltage by "tuning out" the inherent capacitance of the piezo. First, approximate the frequency you'll be working with. (15kHz to 30kHz works well in driving people, bugs, mice, etc., absolutely crazy. ;^) ) A good starting value might be in that range. For now, assume 30kHz. Next, measure the capacitance of the tweeter. The tweeter mentioned above has a series capacitance of 1.2uF. Either a cap meter or a 'scope would work. The way I did it is by using the tweeter itself as a capacitor and substituting different "real" capacitors to get a frequency match on a 'scope. Later testing on a genuine cap meter verified my earlier results, so don't be afraid to experiment. Next, connect up a 555 circuit (or any good oscillator with decent output drive capability). Using the tweeter as the output, and a good 'scope across the tweeter's terminals, check for an output at the selected frequency. You should get the full battery voltage across the terminals. Next, (aha!), calculate the required inductance, using the formula: f = 1 / ( 2 * pi * sqr( L * C ) ) (I think) (For 1.2uF @ 15kHz, I got about 0.5mH. I don't have a calculator handy, so you might want to verify the equation above. If it checks out within an order of magnitude, it's ok.) Get your hands on such an inductor. As a helpful hint, try your best to get one with the largest possible wire size to minimize lead resistance. Inductors from speaker crossovers are usually best. Put that inductor in series with the tweeter and fire the circuit up. Now, you should be able to read close to 75V across the tweeter's terminals... all from a 9V battery! If you want to play around, you can vary the frequency and watch the amplitude peak and fall off in either direction. The only drawback of this inductor approach is that it is now frequency-selective. Still, a 2:1 frequency variation shouldn't cause appreciable falloff. Next, test the circuit in actual use. Try it in a small tank with a dirty part. Then vary the frequency (or look it up, if possible) to get optimal results. When it works on a smaller scale, try it in a bigger tank. If you actually get around to building the bloody thing, you'll have a great sense of accomplishment, believe me! At the very least, you'll have an ultrasonic source which will keep mosquitoes away during the summer, mice in the winter and possibly people all year round, if you lower the frequency to 15kHz ;^) . At any rate... Enjoy! Gene ...!ihnp4!philabs!phri!cooper!gene "If you think I'll sit around as the world goes by, You're thinkin' like a fool 'cause it's case of do or die. Out there is a fortune waitin' to be had. You think I'll let it go? You're mad! You got another thing comin'!" - Robert John Aurthur Halford