Ultrasonic cleaner advice, for cleaning chains before waxing
Some notes from my experience:

If you are in a 220-240 volt country avoid the cheap Chinese cleaners, they are designed for 110 volts and remove a rectification diode as a hack to make it work on higher voltage.  This doesn't work well as the peak voltages are still higher and the output transistors fail.

Secondly, I found ultrasonic cleaning in just water and soap is nowhere near as effective as using a solvent.  I use kerosene, however its very smelly so I only use it outdoors, but it does clean everything well.

Lastly, I haven't noticed much increase in chain life vs just wiping with a rag and oiling the rollers.  Because of this I don't bother ultrasonic cleaning chains unless I am cleaning something else like a cassette.  My theory is the oil aids in flowing out contaminants in the rollers but I have no evidence to back this up.