In the previous post we discussed a piezo transducer element and learned how to use it with electronic circuits. In this article we will see how a piezo tranducer can be driven or operated using a simple circuit.
As discussed earlier a piezo transducer basically requires a frequency to vibrate and reproduce the required sound.
This property makes these devices typically suitable for buzzer related applications and in warning alarm devices.
So does this mean that if we apply a frequency across the terminals of a piezo transducer, it will start generating the intended sound outputs?
Partially this may be correct but might not be as easy as that.
How to Operate a Piezo with Maximum Sound
The applied frequency will be required to be amplified very sharply or strongly before it can actually produce the intended effects in the piezo.
However the amplification procedure is not by using conventional amplifying circuits as used in systems incorporating speakers, but rather it is simply implemented through an inexpensive inductor.
The low power frequency which may be available from a relevant circuit or an IC is first amplified using a transistor, and further more the transistor output is pumped up using an inductor. The use of a inductor becomes the most crucial stage for driving a piezo electric transducer.
The used inductor might not be critical with its value, but the value should as high as possible, the higher the sharper the reproduction from the piezo.
A simple piezo transducer driver circuit or a simple piezo alarm circuit is shown in the following circuit using a NAND gate.
The junction of the 0.01uF capacitor and the 33 K resistor needs to be connected to ground, which is not indicated in the diagram.
Rajthilak Kuppuswamy says
Hi Swagatam,
I am looking to build a simple circuit which can light up a 12v LED strip using piezo. Basically trying to use a piezo attached to a drum and light up the LED attached to it. Please help me out.
Swagatam says
Hi Rajtilak, It can be difficult to light up a 12V LED strip, since a typical piezo (27 mm) will not generate more than 3V at its optimal capacity.
even a boost charger circuit will not be able to help since the current involved with a piezo output could be relatively low
Rajthilak Kuppuswamy says
Hi,
I am not looking to power up the strip with the current generated from the piezo sorry if i had confused you. All i need is using this piezo as a trigger source and get supply from a 12V source. Im still not clear about what i am trying to tell you. I will have a separate 12V DC source, all i need is, when i hit this trigger(piezo) i want the signal to make this strip power up from that 12V source. Please help.
Swagatam says
OK, in that case you can try the following idea
https://homemade-circuits.com/2012/04/how-to-make-sound-activated-alarm.html
just replace the siren with your 12V strip
you can also try a 741 IC as a comparator circuit as shown below and use it for the same
https://1.bp.blogspot.com/-aN-P6GFQTLY/V5i1xPJaCgI/AAAAAAAAOX4/i2egiiAGwMINoDDqK7bYu5vDo6Bh_JF1ACLcB/s1600/741%2Bzero%2Bcrossing.png
connect the piezo across the right side 100k and the 12V line.
connect pin6 with a transistor driver for the LED strip
Unknown says
Hello,
I need a circuit to produce ultrasonic vibrations. The vibrating element (piezo) has to attach the wall of a let's say glass and the vibrations should detach the bubbles attached to the glass wall at a frequency of about 80 kHz. Do you think this configuration will be helpful?
Swagatam says
Hello, yes the last design can be used for the purpose but the piezo will need to be attached correctly so that the vibration do not get dampened
Ephraim Even-Hen says
What value should be the coil for a 35Khz oscillator?
Swagatam says
you will have to determine the frequency by trial and error method by varying the 33K resistor or the capacitor values and confirming the results with a freq meter
Ulhas Rane says
Can third high volume circuit be driven by microcontroller pin generating clock?
Swagatam says
yes you can, feed the clock directly to the base of the transistor via a 1k resistor