555 ultrasound remote control voice doorbell circuit

Published:2011/5/30 8:37:00 Author:TaoXi | Keyword: 555, ultrasound, remote control, voice doorbell | From:SeekIC

As the figure 15-25 shows, the doorbell is composed of the ultrasound launch circuit and the receiving decoding and audio circuit. This circuit can remote control the voice circuit at the distance of 10 meters. The launcher uses the special ultrasound launch integrated circuit NYKD to drive the piezoelectric ceramic ultrasound emission sensor YD1 to send out the 40kHz ultrasonic wave. If you press AN, this circuit sends out a string of modulation ultrasonic pulse wave. The IC3 uses the audio decoder LM567 which has the phase-locked loop (PLL). When there is no signal, the output port pin-8 has the high electrical level because of the R=10kΩ bias, when there is the input signal, it outputs the negative hopping pulse to trigger the IC4 monostable circuit. The center frequency f0 of the IC3 should be set at the 40kHz frequency emission.



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