Bus door-close automatic notification device (555、KD153、KD28) circuit

Published:2011/4/25 9:43:00 Author:TaoXi | Keyword: Bus, door-close, automatic notification device | From:SeekIC

The Bus door close automatic notification device (555、KD153、KD28) circuit is as shown. This circuit is composed of monostable delay circuit, Ding-Dong IC KD-153, dual power amplifier integrated circuit KD-28 and the audio circuit (speaker). The monostable delay circuit is composed of the IC1(555) and R1, C1, R2, C2. When the micro switch K1, K2 is closing, voltage of C1 can not change, 555 reset the place because of the pin-2 is low-level (<1／3VDD), pin-3 outputs the high-level current to conduct BG1, so the KD-153 has power to work, the Ding-Dong signal is amplified by the KD-28 and then drives two speaker to send out voice. When C2's pin-6 has the electric potential of 2/3VDD, 555 resets. The speaker stop working. This period that the speaker send out sound is the monostable circuit delay's td = 1.1R2C2. Change the charge-time constant R2C2, we can adjust the sound of the time.



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