Sean Ragan writes:

Working in a chemistry lab will spoil you to the use of certain tools. An ultrasound bath is one of them. While a proper laboratory sonicator is a fairly pricey piece of equipment, by amateur standards, there are ultrasonic cleaners designed, marketed, and priced for the home market. They are primarily intended for cleaning jewelry, spectacles, and other small parts. The cheapest one I’ve found is manufactured by “Chicago Electric,” a Chinese manufacturing concern, and sold through Harbor Freight. This model, unfortunately, is not equipped with a timer, and as manufactured it will only run for 3-minute cycles: You push the button, you get three minutes of ultrasound. If you want more than that, you have to come back at the end of three minutes and push the button again. This in stark contrast to my old laboratory sonicator, which featured a timer switch that would run the bath for as long as an hour without supervision. So I modified my home sonicator, first by opening the control panel and soldering the start button closed. As shown in the picture, the timer switch is mounted in an expedient plastic case. I’ve run the sonicator for the timer’s maximum period of one hour many times with no problems whatsoever. I’m obliged to disclaim, however, that this device was not intended to run continuously for that long and it may not be smart to wander very far away while it’s in operation.