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Yes this simple transistor circuit can be used as a home door bell and it’s ON time can be set as preferred by the user, meaning if you wanted that the sound of the bell to remain switched ON for a particular period of time, you could easily do it just by adjusting the given pot. The actual tune is derived from the IC UM66 and the associated components, while all the included transistors along with the relay are configured for producing the time delay for keeping the music switched ON.             Parts List R1, R2, R4, R5 = 1K VR1 = 100K, D1, D2 = 1N4007, C1, C2 = 100uF/25 T1 = BC547, T2 = BC557 T3 = 2N2222 Z1 = 3V/400mW Transformer = 0-12V/500mA, S1 = Bell Push IC = UM66

This is the Simple Two 555 Timers Bell Circuit Diagram. This simple scheme uses two Bell 555 timer. The frequency controlled capacitors, which should be preserved are almost identical in value with each other to achieve the best results. Fine tuning is done with the R1 and R2. The decay time is controlled by R3.[ ] Simple Two 555 Timers Bell Circuit Diagram

This is a simple IC based Two 555 Timers Bell Circuit Diagram. This simple Bell circuit uses two 555 timers. The frequency is controlled by the capacitors that must be preserved almost identical in value to each other for best results. Fine tuning is done with R1 and R2. The decay time is controlled by R3. Two 555 Timers Bell Circuit Diagram

Simple Mock Alarm with Call Bell Circuit Diagram is a fully automatic mock alarm to ward off any intruder to your house. The alarm becomes active at sunset and remains ‘on’ till morning. The flashing light-emitting diodes (LEDs) and beeps from the unit simulate the functioning of a sophisticated alarm system. Besides, the circuit turns on and off a lamp regularly at an interval of 30 minutes throughout the night. It also has a call bell facility. The circuit is built around CMOS IC CD4060B (IC1), which has an internal oscillator and a 14-stage binary divider to provide a long delay without using a high-value resistor and capacitor. Press switch S2 to provide 9V power supply to the circuit. During daytime, light-dependent resistor LDR1 offers little resistance and transistor T1 conducts. This drives transistor T2 into the cut-off mode, as its base is pulled to ground via transistor T1. Reset pin 12 of IC1 remains high as long as transistor T2 is cut off. This keeps the oscillator of IC...