After publishing various doorbell project in www.electronicsproject.org by innovative group Dreamlover Technology design a simple, cheap and as well as unique memory call bell. It is unique because it tell us whether any guest come or not in absence of us too.

Circuit description

The entire circuit single chip memory call bell is designed around CMOS quad 2-input NAND gate IC CD4011 (IC₁). The two gate of this IC is configured as RS flip-flop which further formed two complementary – output. When switch SW₁ is pressed the output of flip-flop is changed and LED₁ glow up. The third gate of IC₁ combined with diode D₁ and capacitor C₁ to generate music tone. Transistor T₁ is used as single stage buffer amplifier. Switch SW₂ is used to reset the circuit.

PART LIST

Resistors (all ¼-watt, ± 5% Carbon)

R₁, R₂= 10 KΩ

R₃ = 100 Ω

Capacitors

C₁ = 220 µF/10V (Electrolytic)

Semiconductors

IC₁ = CD4011 (CMOS quad 2-input NAND gate)

D₁ = 1N4148

T₁ = BC147

LED₁ = RED

Miscellaneous

SW₁, SW₂ = Push-to-on switch

LS₁ = Piezo Buzzer