A buzzer is a small sound-producing device that designers use in alarms, toys, and indicators; also this Simple Two Transistor Buzzer Circuit uses only two transistors, making it simple to build and ideal for beginners.
Furthermore, it works with low voltage and because of this it is safe to test, so 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, apply 9V power to the circuit, the circuit then uses one NPN transistor and one PNP transistor, which together 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 through feedback and starts the oscillation and as a result, the circuit generates an AC signal and sends it to the speaker.
Therefore, the buzzer produces a continuous sound while the LED glows at the same time.
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.
- Next, transistor BC547 Q1 emitter pin connects to LED and GND, base pin connects to R1 and R2 resistors and connect collector to base of transistor Q2 through resistor R3.
- Then transistor BC557 Q2 emitter pin connects to positive supply of 9V, connect base to collector of transistor Q1 through resistor R3 and then connect collector to one end of capacitor C2 and one end of speaker.
- Also, capacitor C1 positive connect to positive supply of 9V and C1 negative connect to GND.
- After that, C2 capacitor connect between resistor R2 and junction of collector Q2 and speaker and speaker one terminal connect to Q2 collector and other terminal to ground.
Conclusion:
To conclude, this is a very easy buzzer circuit, which uses minimum components and also its cost is very low; therefore, beginners can try it and moreover, it helps to learn oscillation.
Also, this Simple Two Transistor Buzzer Circuit is useful for learning purpose and finally, it is good for school and hobby projects.