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Utrasonic Cleaner (Assorted High Voltage Circuits): https://www.repairfaq.org/sam/samschem.htm
As NPN power transistor you can use BU208, BU508 or similar, and if you don't have 115V you can employ a transformer with CT primary winding and step down voltage from 230/240 to 115/120 ..
I looked into this once, to save money. The biggest problem is finding a powerful-enough ultrasound transducer. The next is mounting it to the tank effectively so that it will work.
I quickly found out that it was cheaper, and much easier, to buy a used on from eBay. There's not really much challenge, electronically, to making one so it's not a very interesting project, just difficult.
Do you really need ultrasound? What about a high frequency audio tweeter? Powerful ones can be had for little money and might do the job. Depends what you want to clean I suppose.