Single Chip Memory Call Bell

Single Chip Memory Call Bell

After publishing various doorbell project in 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.

circuit diagram of single chip memory call bell


Resistors (all ¼-watt, ± 5% Carbon)

R1, R2= 10 KΩ

R3 = 100 Ω


C1 = 220 µF/10V (Electrolytic)


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

D1 = 1N4148

T1 = BC147



SW1, SW2 = Push-to-on switch

LS1 = Piezo Buzzer