I rescued an old ultrasonic washer from our company’s recycling bin. It’s old and broken but the tank is nicely sized and the power rating is nice (375 W). I opened it and took out my multimeter.

The ultrasonic transducers seem to fried and they aren’t conducting anything. Correct me if I’m wrong but I think that there should be some resistance over them. But in case they all look like fried ones.

I tested the driver board with some random “multimedia speaker” and some noise do come out from the speaker. My multimeter couldn’t read anything from the output lines but this should be normal as the frequency is way out my multimeter’s range.

Then the actual question. The device is using 48 kHz frequency. All reasonably priced transducers seem to be running at 40 kHz. There were some transducers in 50 or 48 kHz range but the prices were annoyingly high.

So would cheap 40 kHz transducers work with a system running at 48 kHz?

eBay seems to be offering quite cheap driver boards too but they start to get expensive after 100 W. And I doubt that wiring several sets in parallel would work at all.