|Location:Home-» Integrated Voice circuits -»Bus communications device automatically closed (555, KD153, KD28)|
Shown for the bus to close the circuit automatically notified . The circuit consists of a single stable delay circuit , Ding Dong IC KD-153, dual power amplifier IC KD-28, audio circuit ( speaker ) and other components. Monostable delay circuit consists of IC1 (555) and R1, C1, R2, C2 component . In the micro-switches K1, K2 together on the instantaneous news , C1 on the voltage not mutation, 555 feet is low because (1/3VDD) The Set occurred ,the output pin high to BG1 turn , the corresponding KD -153 was electric , the output of the Buzz signal amplified by the KD-28 drive two speakers voice .
At the same time . C2 to charge , when the C2 potential charge to make up 2/3VDD, the 555 reset occurs . Corresponding speaker to stop sound . Speaker sound that this period corresponds to a single stable circuit delay td = 1.1R2C2, shows the corresponding parameter of about 3 seconds. Change the charging time constant R2C2,you can adjust sound of the time .