# Making piezo emit heat

Hi,
I my project I need to make piezo buzzer emit heat. I use transistor and DC to DC voltage converter (3.3 to 10V.). When i make square wave signal with signal generator piezo uses only ~7V to start heating. Sadly, when i am doing the same on microcontroller it just does not heat. Plus I cant get high amplitude of noise.
When i connect piezo, there is a voltage dropout on scheme. Could it be problem of impedance? My piezo is 14nF so I tried ~100uH inductor in parallel but it does not help. Worse, it emits heat by itself ( Not piezo but inductor and that is opposity of my need).

Is there some scheme that could help me to get out of this situation? Maybe I just forgot something to add?

14uF is a very large capactive load - your signal generator probably handles more current and it also
true AC (your transistor is not AC so its probably mainly just DC-biasing the piezo, which cannot dissipate
any energy).

Firstly why do you need to heat a piezo buzzer? Why not use a heating element?

What frequency is involved?

Are you at risk of mechanical damage by driving high powers into the buzzer? I'd have thought its
a risk.

Sorry nF*. It is science project and i use resonance frequency of 6.5 kHz.
Mechanical damage is not problem at my case.

Piezo uses very low current, my microcontroler can handle it easily

I use transistor and DC to DC voltage converter (3.3 to 10V.).

What’s that for? Is that to power the Arduino or is that between the Arduino and the Piezo?

Since you have 10V available you can use a transistor or MOSFET to boost the Arduino’s 5V output to 10V. If you double the voltage you also double the current and that’s 4 times the power. Or, you can use an H-bridge for 20V peak-to-peak.

Piezo uses very low current, my microcontroler can handle it easily

Heat requires power. If you’re are significantly heating anything directly with an Arduino I/O pin you are probably exceeding the current specs.

Power = Voltage x Current (assuming a resistive load).

Current = V/R. (or V/X) ([u]Ohm’s Law[/u])

Capacitive Reactance (in Ohms) = XC = 1/(2PIFC), where capacitance is in Farads [u]Here’s an online calculator[/u].

My piezo is 14nF

That’s an approximation. Pure capacitance doesn’t consume/dissipate power and it won’t generate heat or sound.

Why not use a resistor to heat?

Nicalai:
Sorry nF*. It is science project and i use resonance frequency of 6.5 kHz.
Mechanical damage is not problem at my case.

Piezo uses very low current, my microcontroler can handle it easily

The current won't be low at resonance, that's the whole point surely? The
thing can't heat up without resonance as the current would be a couple of mA
given the 14nF's impedance at 6.5kHz

You've edited the original posting directly so that my comment about 14uF looks
silly and the thread fails to make sense.