This circuit is characterized by the fact that the oscillation frequency is determined by the ceramic capsule itself. Operating at its resonant frequency, the buzzer has a higher output, thus producing a higher intensity sound.
The potentiometer controls only the oscillation point, thus serving as a sort of volume control. The buzzer is a high impedance ceramic capsule. In figure 1 we have the complete diagram of the oscillator.
The assembly can be made based on a small bridge of terminals or even in matrix of contacts. In figure 2 we show the bridging of terminals.
The power can be made with voltages of 6 to 12 V obtained from batteries, battery or source. This circuit can be used in signaling, call systems and small alarms.
Material list
Q1 - 2N2646 - unijunction transistor
BZ - Ceramic transducer
P1 - 100 k ohms - potentiometer
R1 - 1k ohms x 1/8 W - resistor - brown, black, red
R2 - 470 ohms x 1/8 W - resistor - yellow, violet, brown
R3 - 10 ohms x 1/8 W - brown, black, black
Miscellaneous: battery holder, battery or source connector, terminal strip, wires, solder.
