About amplifier circuit


I take piezo that arduino ultrasonic board has.
This piezo is similar with so I replace it capacitor in circuit diagram.
And want to make energy transfer and data transfer device.

(I'm sorry I don't know how to rotate picture)

The problem is
It is working well at not amplifier circuit like upper diagram.
I check it with oscilloscope and it working well with 200mV peak.

But I want to make circuit 36V not a 5V that inital arduino voltage.
So I make N-mosfet amplifier but it seems that not working.

I think the -(minus) voltage is a reason that made by capacitor.

Does there any way to solve my problem??

Replace that capacitor between MOSFET and 36V with a resistor and you get your signal as 36V block wave.

If you want to draw any significant current from that 36V wave you need a different circuit.


Tie the drain to 36 via a pull-up resistor
Polarise the gate so as to have its potential by the threshold of the fet. You can do it with a high value resistor from gate to drain

Good luck

A piezo is basically a capacitor.
If you drive it single-ended, then the first pulse will charge the piezo to 36volt and it won't discharge anymore,
resulting in little or no voltage on the fet and no power into the piezo.
You need to drive that piezo with a push-pull amplifier stage.
A low value resistor across the piezo is also a solution, but not as good.


I think that if you tie the drain via a pull-up resistor should do the job.

I think that if you tie the drain via a pull-up resistor should do the job.

Isn't that what "A low value resistor across the piezo" is?