Ultrasonic humidifier

[Doug]

Reading these threads this group is a wealth of information.
Before I replace this unit I thought I would look into it.
It has about 50vpp 2mhz drive to the piezo.
Seems correct
The driver transistor is hot.
Maybe normal .
I assume I could test the piezo with a generator and oscilloscope.
I don't have at home a generator that goes to 2 mc.
Should be able test the piezo with gen and scope all in parallel should peak at resonate frequency correct?

 

[danadak]

Yes, sweep freq from low to high and look for resonance.

If your scope has a gate output it can function as a generator, just a thought. Maybe use a 2 stage rc
filter on output to get a more sine stimulus.

A DIY generator - https://github.com/pstimpel/functiongeneratordds Search on ebay for
AD9833 and you will see several low cost boards to make life easy.

Or Nano VNA, many versions, on ebay and amazon. Double check min freq operation however.


Regards, Dana.

 

[Doug]

Thanks 4 info

 

[Buk]

Know that piezo elements have two resonance frequency levels. One at its maximum admitance where it runs most efficiently, and one at its minimum admitance, where it may deliver slightly more power, but use considerably more energy; also known as the anti-resonace point.

See this for a more thorough explanation along with a detailed procedure for determining both.