Ultrasonic mister using a Piezoelectric disc with water sensor

Thread Starter


Joined May 24, 2021
Hi All,
I'm trying to put together an ultrasonic mister, but with a water sensor for the garden. The disks break if there's no water on them at these frequencies( 113khz) so I'm trying to combine a couple of circuits together. Unfortunately it's been a long time since I played with electronics and I'm rustier than the Titanic, although I hope a little more successful :)

Here's the circuit I found for the Piezo disk to oscillate and create the mist , Full credit to the original designer here https://creativetech1010.blogspot.com/2020/05/mist-maker.html
View attachment 239487
It's pretty straightforward, although it needs a 12V supply. The circuit for the water sensor is here, again full credit to the original designer https://www.instructables.com/Simple-Water-Sensor/
View attachment 239490
I was thinking of putting a beefier NPN transistor to effectively allow me to replace the LED with the mister circuit.

Am I on the right lines, and if so, what NPN would you recommend? If I'm totally out, what would you suggest?