Need opinion on a circuit approach for a project. I need to drive a piezo disc at 1Mhz at ~80v & ~1 amp. Circuit powered by a 12v car battery via voltage regulator.

Design approach I have thus far:

- 1mhz square wave generated by high speed 555
- signal in to MOSFET driver (I have a MAX4420 handy)
- Output to Gate of MOSFET
- Source of MOSFET to primary of step up transformer
- Secondary of transformer connected to piezo

Most of the design examples I've seen similar to this are for lower frequency, lower voltage applications. I'm a little concerned about heat and noise.
Appreciate any comments. Cheers!

 

What noise? Is there something in your design that will vibrate? 1 MHz sound is not audible. Do you have a part number for your mosfet yet? Will it be P- or N-type?

John

 

Iḿ also looking for the same circuit. I tried with some rf transistors but no luck reaching it. Also i tried with IRF840 mosfet with IR2102 driver switching at 1MHz. My load right now is a resistor (about 100k) and i cant get that all VCC of my Power Supply (about 170VDC) pass for my load.

The current that should pass is I = 170/100,000 but in my load I only can see a triangled signal with about 3Vp-p. Seems like the impedance of the conmutation frequency is too high? How is this called (to google it and find solutions)? How i can solve it?

Any idea?

Note: First im trying this (a resistor as my load) because is dangerous to put directly my piezo transducer. (maybe it will blow if I connect too much DC).

 

Do you know your transformer was designed to be used at this frequency? A little core and copper loss coupled with some leakage inductance can kill a high frequency signal easily.