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Need help getting Piezo Atomizer circuit working

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MatCat:
Attached is current schematic of the design. 

J6 is the Piezo element, it is rated to run at 1.7Mhz, and should draw about 25 watts at 24v.  C23, 27, 28, 29, and 30 are there for flexibility in trying caps, the circuit calls for 3.3nF, which currently is being handled by a single film cap (C98162 on LCSC).  L4 and L3 are there to allow flexibility in the 2uH specified inductance, currently I am using a 1uH inductor (C165771 on LCSC)  and an adjustable inductor that can go from 0.8uH to 1.6uH.  Trying various cap values, adjusting the inductor, trying a few different transistors, I just can't seem to get this piezo to function as it should (It should atomize water and create fog when operating properly.).    Also of oddness visible in the second attached image is that there is a weird 50Khz oscillation going on as well.

MatCat:
Wow, I have to say, I have been struggling to get a circuit to drive this piezo for months now, and I am not the only one, this forum, and a few others all have dead discussions by others trying to get it to work, come on guys, take up  a challenge, let's get a workable circuit figured out that the entire internet can use :).

duak:
Is this circuit from an app note?

A few things:

- I don't see any bypassing on +24V to GND.  I would add a couple of 100n as well as a 10 or 22 uF electrolytic.

- R25 provides a base current to Q14 of 24 V / 470R = 51 mA  The minimum hFE is on the order of 50 so the collector current would be something like 2.5 A.  This would give a static dissipation of 60 W which is almost at its dissipation limit.  I would increase R25 to something like 2K2 or 3K3 and see what happens.

- R30 seems a bit low.

- what are L3 & L4? Unless they are toroids, is there any chance their magnetic fields are interacting?

If you have a signal source I suggesting breaking the feedback loop at C22 & L2 and injecting a sine wave into it and then observe the voltage on R30 while varying the frequency.

MatCat:
I actually paid someone a small fee to help me figure out a circuit from an app note, he came up with this circuit and managed to make it work with random bits and bobs he had and DIY inductors, I am trying to get it to work with readily available components (mostly SMD).

The 24V rail has bypass elsewhere, you are only seeing the atomizer specific aspect of the circuit.

The piezo is spec'd to run at 25W, I will have to look at that on the resistor...

I honestly don't know enough about this circuits operation to fully understand what R30 is doing.

L3 is C165771 on LCSC, and L4 is typically an adjustable inductor.

I do have a signal source, I will have to experiment with that when I get the time in a few days.

MatCat:
Been a WHILE since I posted, going to bump this thread.

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