This circuit consists of a well-known oscillator configuration with complementary transistors, explored at other times on this site. The differential in this case is that we show the assembly in a solderless board.
The circuit produces clicks at regular intervals that can be set in the potentiometer. The sound of these clicks serves to help keep pace in gymnastics, running or even playing some instrument.
The circuit can be powered with voltages from 3 to 6 V in the original version and changing Q2 by a BD136 we can supply with voltages up to 12 V obtaining higher power.
The frequency also depends on C1 which may have its value changed over a good range of values. The switch is optional and the circuit can be installed in a small plastic housing.
In figure 1 we have the complete diagram of the metronome.
In figure 2 we have the assembly on a terminal bridge.
In figure 3 we have the assembly in an array of contacts, ideal version for technical courses or initiation to electronics.
To test the circuit, simply power the unit and set P1 so that the loudspeaker produces intermittent clicks.
Material list
Q1 - BC548 - NPN general purpose transistor
Q2- BC558 - PNP general purpose transistor
S1- Single switch - optional
B1 - 3 to 6 V- 2 to 4 batteries of any size
FTE- 4 or 8 ohm - small speaker
P1 - 1 M ohm - potentiometer
R1- 10 k ohm x 1/8 W - resistor - brown, black, orange
R2- 1 k ohm x 1/8 W - resistor - brown, black, red
C1- 10 uF x 12 V - electrolytic capacitor
C2- 100 uF x 12 V - electrolytic capacitor
Miscellaneous:
Terminal block or contact array, battery holder, mounting box, potentiometer knob, wires, solder, etc.
