Audio remote control switch schematic

Posted on Dec 11, 2010

Each issue a specific frequency of sound, audio remote control will switch changes state, the circuit for other frequencies emitted by the environment sound with strong anti-in

Audio remote control switch schematic
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terference ability. (1) circuit principle 1) phase locked loop circuit principle: CD4046 PLL circuit includes a phase comparator, a low-pass filter and a voltage controlled oscillator section 3 group into. The phase comparator function is outside the sound signal with the center frequency of the internal pulse signal frequency comparison + when the same frequency, the output from the first O feet high potential; whether it is internal or external sound signal oscillation signal whose frequency It will have to unlock like state. In order to solve this. Problem, phase-locked loop circuit through the filter of the phase comparator output voltage feedback voltage to the oscillator to change the frequency of the internal oscillator pulses, so that the frequency of the external signal is the same; that starting from the unlock state to the final Lou set of allowed state of the input signal frequency range is called the frequency capture range. CD4046 pin shown in Figure 18-43a. CD4069 hex inverter pin diagram shown in Figure 18-43b. Fig. 1 PH11 signal input; PHlZ the comparison signal input terminal {VC01 for the VCO control terminal; INH to prohibit the end; Z is the internal zener negative terminal} DEMo demodulated output terminal; R2, Rz is external resistor end; G, G for the external capacitor end; PH01, PH02 for the phase comparator - Guo ln} PH03 output of the phase output terminal, when the lockup high, low loss of lock when almost; vCOo as a voltage controlled oscillator output terminal 2) principle analysis: circuit can whistle sound as a transmission signal, the remote control. Received by the microphone BM, adjusting circuit receiving frequency, so that the circuit only respond to a specific whistle sounds. Carefully adjusted so that the circuit the highest sensitivity, control distances. As if the producers have more experience, you can also use the mouth blowing a whistle to adjust the circuit. Receiving circuit shown in Figure 18-43c. Hex inverter circuit by the CD4069 and CD4060 14 in hex serial counter/divider and other components audio amplifier circuit, PLL circuit and a switch output circuit. Audio amplifier sound microphone signal was subjected to amplification. External sound signal after amplification to the input of the PLL circuit. PLL has an internal voltage-controlled oscillator, flat while working on the set operating frequency. When the external audio signal successor PLL circuit, and every time it receives the VCO operating frequency when the same audio signal, phase locked loop circuit is in a locked state, the voltage output of the circuit changes from low to high, the output of the control switch circuit change switch status.

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