An electronic buzzer circuit is simple. But useful well worth and the price is lower than 1$. By using just a 9-volt battery only. So without worrying about electrical leakage or an electric shock from 220V to a buzzer. Unless also has LED will glow. Show that the circuit the normal operation as well.
How buzzer circuit works
From circuit in figure 1 will see that we use both transistors, which are matched pair transistors(CS 9012, CS9013), works together with a few resistors, capacitors. In as the oscillator circuit build sound signal frequency.
Figure 1 the simple electronic buzzer circuit by two-transistor
By has both resistors- R=1.2K and C=0.047uF to set the output frequency. Which can change slightly the value of both components, so the output sound changed. However, from the experiments, this value will be the best frequency.
The components list
CS9012: 50V 0.8A PNP Transistor
CS9013: 50V 0.8A NPP Transistor
*** for transistor please read note:
C-0.047uF 50V_Ceramic Capacitors
C-33uF 25V or 47uF 25V or 10uF 25V
0.25w 5% resistors
R-50K or 56K
R-120Ω or 100Ω
R-1.2K or 1K
LED: any color as you want
Piezo speaker,9-volt battery, PCB, and others.
How to use transistors
You can use any transistor number for example
NPN type: 2SC1815,BC547,2N3904
PNP type: 2SA1015,BC557,2N3906
But Position legs mismatch please be careful. as Figure below.
Making Buzzer circuit
This project uses a few components and easy. So you can assemble them on perforated board or universal PCB board.
But if you would like to build PCB. You can also see the copper foil track layout of this project. (actual size) the prototype board as Figure 2 and Figure 3 is the components layout.
This circuit use a voltage supply of 9V. So, normally it can use 6V to 12V.
All resistors use size ¼W.
Loudspeaker use size of 2 inches 8 ohms 0.25 W
You can listen to it in the video below.
Increase the buzzer loudness
A Simple loud buzzer circuit (trembling sound) is creating a kind of ring circuit that provides a strange sweetness of general bell. It uses all-transistor so easy to builds and cheap, suitable for bedroom or a private room good or may be adapted into a bell. Listening to children play leisure. In addition melodic sound then. Also has LED light flashes with the beat shakiness of the sound as well.
The working principle
In the circuit, we will divide into two sectors work together. Firstly, as low frequency oscillator. Secondly, will be sound frequency oscillator.
On this second section include two transistors are CS9012, CS9013 are set as the audio frequency oscillator has out of 1200 Hz to a speaker. And some current from transistor will through to LED.
So, when the sound signal occurs. The LED1 will also glow. But The latter circuit will connect through pin C of Q2. So, if Q2 not conducted current, this circuit will not generate sound.
In that first section. There may be Q1 and Q2 connect together with R, C as the multivibrator oscillator.
They generate low frequencies of 5 Hz. So, Q2 will conduct and stop current with speed of about 5 Hz per minutes. It causes the second section generates a frequency out of sounds is approximated, sonorous, clear melodic quite vividly.
Building louder buzzer
This circuit use power supply of 9V. All resistors use ¼ W of size. The speaker 8 ohms size 2 inch 0.25 watts.
This project use a few components. So we can assemble on the universal PCB board. But we can make a PCB layout see as below. (LEFT)
Then, the wiring for circuit wiring and various components can view of the example in Right.
Watch out! carefully for is the polarity of the electrolytic capacitors and Pin of the transistors are not an error.
Single-sided PCB layout(left) and The components layout of this projects.(Right)
The components List
0.25W Resistors, tolerance: 5%
R6: 330 ohms
Q1: 2SCC1815, C945, C458, NPN transistor
Q2, Q3: CS9013 or equivalent_NPN transistor
Q4: CS9012 or equivalent_PNP transistors
C1, C2: 10uF 16V
C3: 1uF 16V
C4-0.047uF 50V, Ceramic
LED1: Any color as you want.
SP1: Speaker 8 ohms 2 inch 2 watts
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