Small piezoelectric (ceramic) buzzers do not have a lot of sound power and are suitable for more modest applications such as alarm clocks, clocks, car and computer warnings. We can, however, increase the sound power of such a buzzer by using an electromechanical feature, a simple relay.
The voltage induced in the relay winding at the switching is often greater than the voltage supplied for its power supply, which can then mean a good increase in the sound power of the buzzer if it is applied to that element.
The relay itself acts as a vibrator, determining the operating frequency of the system which becomes very simple and compact. In figure 1 we have the complete diagram of the vibrator with the buzzer.
The actual appearance of the assembly is shown in figure 2.
In the figure we take as an example a 6 V relay with DIL base from Metaltex, but other types can be used, with voltages of 12 V provided they have reversible contacts.
The capacitor determines the frequency of the emitted sound, being able to be used types of 10 nF to 220 nF or even more, according to the characteristics of the used relay.
Material list
BZ- Piezoelectric transducer - buzzer (without oscillator)
K1- 6 or 12 V relay with 100 or 50 mA current - Metaltex
S1 – Push Button
B1- 6 V or 12 V - batteries or power supply
C1 - 10 nF to 220 nF - ceramic or polyester capacitor
Miscellaneous: support of batteries, wires, solder, etc.
