Audio remote control switch schematic diagram

Every time a sound of a specific frequency is emitted, the audio remote control switch
will be controlled to change state. The circuit has strong anti-interference ability against sounds of other frequencies in the environment .
    (1) Circuit principle
    1) Phase-locked loop circuit principle: CD4046 phase-locked loop circuit consists of three parts: phase comparator, low-pass filter and voltage-controlled oscillator
. The function of the phase comparator is to compare the frequency of the center frequency of the external sound signal and the internal pulse signal + when the frequencies are
the same , a high potential is output from pin ①; whether it is an external sound signal or an internal oscillation signal, its frequency All will occur in the out-of-lock state
. In order to solve this. Problem, the phase-locked loop circuit can feed back the voltage output by the phase comparator to the voltage oscillator through the filter, changing
the frequency of the internal oscillation pulse to make it the same frequency as the external signal; this changes from the initial out-of-lock state to the final
The input signal frequency range allowed by the fixed state is called the frequency capture range. The CD4046 pin diagram is shown in Figure 18-43a. The pin diagram of the CD4069 six-inverter
is shown in Figure 18-43b.
  1 In the figure, PH11 is the signal input terminal; PHlZ is the comparison signal input terminal {VC01 is the voltage controlled oscillator control terminal; INH is the inhibit terminal; Z
is the negative terminal of the internal Zener tube} DEMo is the demodulation output terminal; R2 and Rz are External resistor terminals; G and G are external capacitor terminals; PH01 and PH02 are
phase comparison - ln output terminals} PH03 is phase output terminal, high level when locked, low level when locked; vCOo is a voltage controlled oscillator Output end,
    2) Principle analysis: The circuit can use whistle sound as a signal transmitter for remote control. It is received by the microphone BM and
the receiving frequency of the circuit is adjusted so that the circuit only responds to the specific whistle sound. Carefully adjust the circuit to achieve the highest sensitivity and the longest control distance. If
the maker is more experienced, he can also use his mouth to whistle to adjust the circuit.
    The principle of the receiving circuit is shown in Figure 18-43c. The circuit consists of CD4069 six-inverter and CD4060 14-bit serial counter/frequency divider
and other components to form an audio amplifier circuit, a phase-locked loop circuit and a switching output circuit. The audio amplifier circuit amplifies the sound signal obtained by the microphone
. The external sound signal is amplified and then connected to the input end of the phase-locked loop circuit. There is a voltage-controlled oscillator inside the phase-locked loop circuit, which usually
works at the set operating frequency. When the external sound signal is transmitted to the phase-locked loop circuit, whenever
the sound signal with the same operating frequency as the voltage-controlled oscillator is received, the phase-locked loop circuit is in a locked state, and the voltage of the output circuit changes from low to high, controlling the switch output circuit. Change
switch status.