When you think of ultrasonics,  you probably think of a cleaner or maybe a toothbrush. If you are a Star Trek fan, maybe you think of knocking out crew members or showers. But there is another practical use of ultrasonics: cutting. By vibrating a blade at 40 kHz or so, you can get clean, precise cuts in a variety of materials. The problem? Commercial units are quite expensive. So [Electronoobs] decided to roll his own. Check it out in the video below.

There are dreams and then there’s reality. Originally, the plan was for a handheld unit, but this turned out not to be very practical. Coil actuators were too slow. Piezo elements made more sense, but to move the blade significantly, you need a larger element.

Taking apart an ultrasonic cleaner revealed a very large element, but mounting it to a small blade would be a problem. The next stop was an ultrasonic toothbrush. Inside was a dual piezo element with an interesting trick. The elements were mounted in a horn that acts like an ultrasonic megaphone, if you will.

These horns are available, and he found an off-the-shelf solution with four piezos and a large horn that seemed promising. Driving the elements, though, requires a 40kHz 100VAC signal. His original board didn’t work — but he’s not giving up. But, for now, he used a simple circuit on a breadboard. However, it didn’t make a strong vibration, even with a larger horn.

Comparison with ultrasonic cleaners showed that his output voltage wasn’t enough. The expedient answer was to buy an ultrasonic cleaner kit (who knew they came as kits?) and use the boards from it to drive the horn and the blade. That worked very well.

His current thinking is that the cleaner driver may be too large, since the blade and horn get hot in use. But he still encased it with a 3D printed case and wound up with a usable tool. His next version should be portable and maybe run a little cooler.

Ultrasonic sensors are, of course, super useful. Or you can always levitate tiny things with it.