Forming an electronic doorbell circuit based on a 555 timer chip

Memory chip

The function of the 555 timer is mainly determined by two comparators. The output voltages of the two comparators control the state of the RS flip-flops and discharge tubes. Apply a voltage between the power supply and ground. When the 5 pin is left floating, the voltage at the non-inverting input of the voltage comparator C1 is 2VCC/3, and the voltage at the inverting input of C2 is VCC/3. If the voltage of the trigger input terminal TR is less than VCC/3, the output of the comparator C2 is 0, and the RS flip-flop can be set to 1 to make the output terminal OUT=1. If the voltage at the threshold input terminal TH is greater than 2VCC/3 and the voltage at the TR terminal is greater than VCC/3, the output of C1 is 0, and the output of C2 is 1. The RS flip-flop can be set to 0 to make the output 0 level.