2B-TOUCH SWITCH MUSICAL BELL
This is an interesting electronic project. Once you touch the ” Touch Point” the bell rings giving very pleasent and sweet sound. You can use this machine as door bell, alarm or keep with your cash box. The project works on 3 V DC.
TECHNICAL DESCRIIPTION AND WORKING:-
This project has been developed and successfully tested OK in TV Engineer Technical Lab.
The Circuit diagram given below is based on IC 3482 which operates on 3 Volt DC. The current consumption of this project is very low [ma].In addition , two transistors BEL 187 [TR2] and BC148 [TR1] have been utilised. The base biasing of TR2[BEL 187} remains idle as long as point the touch point is not touched. Once the touch point is touched, base gets proper biasing and conducts. Once the transistor conducts, the IC 3482 gets required voltage and the output signal of the IC is available through its pin No 11. This output signal is very week to drive the speaker. As such transistor TR1 [BC 148] is added to amplify the signal.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
- Check all the components as per circuit specifications.
- Pay proper attention to collector, base and emitter of transistor before mounting.
- Check anode and cathode of diodes.
- Check for print short after soldering.
LIST OF COMPONENTS
R1 3M3 1
R2 5K6 1
R3 100K 1
C1 33PF 1
BEL 187 1
BC 148 1
IC UM 3482 1