A trembling sound buzzer circuit is create a kind of ring circuit that provide a strange sweetness of general bell. It use 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 figure 1 we will divide into two sectors work together. Firstly, as low frequency oscillator. Secondly, will be sound frequency oscillator.
Figure 1 Trembling sound buzzer circuit
Thus when the sound signal occurs, LED will also glow. But The latter circuit will connected through pin C of TR2. So if TR2 not conducted current, this circuit will con not generate sound.
In that first section will use TR1 and TR2 connect together with R, C as the multivibrator oscillator to generate low frequencies of 5 Hz. Thus TR2 will conduct and stop current with speed about 5 Hz per minutes. Causes circuit in the second section generate frequency out of sounds is approximated, sonorous, clear melodic quite vividly.
How to builds
This circuit use power supply of 9V. All resistors use ¼ W of size. The speaker size 2 inch 0.25 W. 8 ohm.
This project is not used many components so can assemble on the universal PCB board. But can make a PCB layout see as Figure 2. (LEFT) Then the wiring for circuit wiring and various components can view of the example in Figure 2(Right). look out carefully for is the polarity of the electrolytic capacitors and Pin of the transistors are not an error.
Figure 2 Single-sided PCB layout(left) and The components layout of this projects.(Right)
The components List
TR-C1815 or C945 or C458_______NPN transistors_____2 pcs.
TR-CS9013 or equivalent_______NPN transistors_____1 pcs.
TR-CS9012 or equivalent________PNP transistors_____1 pcs.
C-10uF 16V_____Electrolytic capacitors_____________3 pcs.
C-33uF 16V_____Electrolytic capacitors_____________1 pcs.
C-0.047uF 50V____polyester capacitors______________1 pcs.
other see text.