555 audio equipment automatic shutdown circuit

Published:2011/6/7 20:46:00 Author:TaoXi | Keyword: 555, audio equipment, automatic shutdown | From:SeekIC

As the figure 14-22 shows, the automatic shutdown circuit uses the 555 monostable delay circuit as the core. The monostable delay circuit is composed of the 555 and R6，C5, the delay time td=1.1R6C5, the figure parameter is about 2 minutes, when the audio equipment has no output sound for 2 minutes, the circuit will shutdown automaticly. When the signal gets into the circuit from the R or L port, the VT1 or VT2 amplifies the signal, and this signal is doubled and rectified by the D1 and D2 to conduct the VT3, and the D3 conducts, pin-2 of 555 has the low level (<1/3VDD), the 555 sets, pin-3 has the high level, VT4 conducts, J closes, the audio equipment gets power to work.



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