s far back as the early 1980s looked into building an ultrasonic bath and still have a copy of an article which appeared in Everyday Electronics back in 1981. I saw it being demonstrated at a 'hobby electronics' exhibition in the days that there were such things. It only had a small bath - about as large as you could put a watch or a few coins in. The firm that supplied the transducer and other bits (coils and transformers) went out of business when their factory burnt down.
That was in pre-internet days so you couldn't just goggle 'ultrasonic transducers' to find out where they could be bought from. I had thought I might try to make a go of it, but it also used a couple of obscure looking coils with no details of their inductance etc. I assume that they were the 40kHz oscillator, then the resultant frequency was amplified to excite the transducer.
I'm surprised that EPE, (or more likely, 'Silicon Chip' - the innovative magazine from down-under, where most EPE articles seem to emanate from these days), haven't published a design for one. S.C. did run a project for which Jaycar list a kit for an ultrasonic anti-fouling device for boat hulls. (Seems a bit of a tall order for a relatively small amount of ultrasonic power to vibrate a boat hull sufficiently to annoy and deter barnacles!).
In recent years I've tried the 'joke' ultrasonic baths sold by discount stores, Maplin etc. Low amplitude and cut off on a timer after 3 mins, presumably because they're so inadequately designed that the transformer or whatever risks being overheated. I bought two in succession - one from Lidl, one from Maplin. They're having a laugh, surely? Neither made any impression whatsoever - soap and water would be just as effective for small tasks, so both went back the same day for a refund.
Having watched a video of a 'proper' small commercial/industrial bath being used to clean a dismantled carburettor and been impressed by it, I bought one (a Christmas present to myself in 2010!) from Allendale Electronics who do a whole range in various capacities. The one that I bought has a 2 Litre tank, is 70 Watts, has a thermostatic adjustable heater, a timer for up to 80 minutes, and a digital display. It cost £102 inc VAT, and though it's a lot to pay for something used only occasionally, as ultrasonic baths go, it's excellent value for money, given that a 50 Watt transducer and board alone from Hong Kong costs £46.99. Vat free of course if it comes 'under the radar and you don't get clobbered!
I started a thread last year, which ran its distance and can be found here:
http://golbornevintageradio.co.uk/forum/...p?tid=2124&highlight=Ultrasonic
The bath that I bought which 'tickled my fancy' is presently shown as 'out of stock' at Allendale:
http://www.allendale-ultrasonics.co.uk/u...acity.html