This project is a novelty in the electronic field. Up till now electric bell was being used. In the context of changing times this digital bell is a new project of its own kind. The output from the digital IC can drive a speaker with very good quality of sound. The main attraction of this project is that current consumption is very less.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Technical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
Household electrical bell gives a very distorted and loud sound. It is not liked by the most of the people,. Children are afraid of its sound. This project solves these problems and gives very sweet digital sound. That is why this bell is called digital bell. In this project two CMOS IC [CD4011[ are used. First acts as a touch switch and second works as oscillator. The gate 2A and gate 2B produces 10Hz frequency, when ON/OFF switch is pressed. Further this 10Hz works through gate no. 2C and 2B and change to square wave frequency of 5Khz. This is made ON/OFF by the square wave. Transistor BC147 and BC187 amplify this frequency and it is heard in the speaker.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT :-
- Do not solder CMOS IC directly on PCB, use IC base.
- CMOS IC gets spoiled due to anti-static charge. it should not be touched by bare hands because there is possibility of human body being charged with anti-static charge.
- While soldering transistor check its collector, base and emitter with multimeter.
- Take care of anode and cathode of diode while soldering it on PCB.
- Do not solder IC directly on PCB because there is possibility of getting its spoiled due to leakage current from the soldering iron.
LIST OF COMPONENT
10E=1, 47K=1, 39K=1, 270K=1, 680K=1, 1 MEG=1, 4M7=1, 860E=1
1Kpf=1, 1mfd/16V=1, 4.7mfd/16V=1
IC CD4011=2, IN4007=3, BC547=1, AC187=1
IC BASE [14 Pin]=2, Push To ON Switch =1
Cabinet =1, DC Supply =1