A buzzer is a small sound making device that is used in alarms, toys, and indicators.
This Simple Two Transistor Buzzer Circuit is very simple and easy to make.
It uses only two transistors and therefore, it is good for beginners.
Also, it works with low voltage and because of this it is safe to test.
Now, let us understand the circuit clearly with it design and working.
Circuit Working:
Parts List:
| Components | Values | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt) | 56k, 100Ω, 1k | 1 each |
| Capacitors | Electrolytic 47µF 25V | 1 |
| Ceramic 0.047µF | 1 | |
| Semiconductors | LED any color 5mm | 1 |
| Transistor NPN BC547 | 1 | |
| Transistor PNP BC557 | 1 | |
| Piezo Speaker 8 ohm | 1 | |
| 9V Power Supply/ 9V DC Battery | 1 |
At first, the 9V power is applied to the circuit.
The circuit uses two transistors, one transistor is NPN type and the second transistor is PNP type and together they form an oscillator.
Then the capacitor C1 starts charging and after that the base current flows to transistor Q1 and so Q1 turns ON.
Now, Q2 also becomes active because of feedback and oscillation starts.
As a result the AC signal is generated and this signal goes to the speaker.
Therefore the sound is produced and at the same time the LED glows.
Thus, the buzzer works continuously.
How to Build:
To build a Simple Two Transistor Buzzer Circuit follow the below connection steps:
- First, start by collecting all the parts as shown in circuit diagram above.
- Transistor BC547 Q1 emitter pin connects to LED and GND.
- Base pin connects to R1 and R2 resistors.
- Connect collector to base of transistor Q2 through resistor R3.
- Transistor BC557 Q2 emitter pin connects to positive supply of 9V.
- Connect base to collector of transistor Q1 through resistor R3.
- Connect collector to one end of capacitor C2 and one end of speaker.
- Capacitor C1 positive connect to positive supply of 9V.
- C1 negative connect to GND.
- C2 capacitor connect between resistor R2 and junction of collector Q2 and speaker.
- Speaker one terminal connect to Q2 collector and other terminal to ground.
Conclusion:
To conclude, This is a very easy buzzer circuit.
It uses minimum components and also its cost is very low.
Therefore, beginners can try it and moreover, it helps to learn oscillation.
This Simple Two Transistor Buzzer Circuit is useful for learning purpose and finally, it is good for school and hobby projects.