The 555 touch audio circuit

Published:2011/6/16 2:18:00 Author:TaoXi | Keyword: 555, touch audio | From:SeekIC

As the figure 14-26 shows, the monostable trigger and the multivibrator are composed of a double-time base 556 and some RC components. When the hand touches the sheetmetal M, the induction signal of human body adds to the trigger port pin-6 of IC through C3, so the circuit is triggered, the output port pin-5 of this time base circuit is from the low level to the high level. Because the astable multivibrator's time base circuit reset port pin-10 has the high electrical level, so the oscillator starts working, the oscillation frequency is between 300～4500Hz, so the speaker sends out the sound. When the monostable circuit is triggered, the power supply voltage charges to C1 through RP1 and R2, the delay time td=1.1(RP1+R2)C1.



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