First, let's look at these five components: VT 1, VT2, R 1, R2 and R3. Their main function is to provide bias voltage for ultrasonic sensor (UCM-40R) and amplify the received signal. The front VT 1 constitutes a small signal amplifier, which mainly amplifies the amplitude. The latter VT2 constitutes an emitter follower, which mainly amplifies the power to promote the normal operation of the latter circuit.
These are just preamplifier circuits, and then the circuit composed of LM567 is the frequency discrimination circuit. Its main function is to make the output low when the input signal is at the specified frequency (that is, to connect the negative electrode) and high at ordinary times (to connect the positive electrode). LM567 here is an audio decoding integrated circuit, which is mainly composed of PLL and frequency discriminator. (A detailed explanation can be found in the instruction manual of this component). Its main use in this circuit is a "frequency switch". The related components around it are C 1, C2, C3, C4, R4 and RP1; Among them, C 1 is mainly used for isolation (DC component is not allowed to pass, only AC component is allowed to pass), and the related circuits in RP 1, C2 and LM567 form an RC oscillator (RP 1 factory debugging is adjustable), C3 is a low-pass filter capacitor, C4 is an output filter capacitor, and R4 is a bias resistor (usually responsible for outputting high level).
The next stage circuit is a monostable circuit composed of 555 (single time base integrated circuit), whose main function is to shape the waveform output by the previous stage (at the same time, it also plays the role of "eliminating jitter" on the input signal. Because the input part of its transmitting circuit is a simple button, when people press the button, it will always shake, resulting in continuous and irregular interference pulse output, so that many trigger signals are generated in a very short time, which makes the equipment mistakenly controlled. So pulse shaping and dithering are needed here). His working principle is that when the input level is low, its output will output a high level, and it will always output (no matter how the input terminal changes at this time, its output will always be a high level) until it exceeds a certain time (the time depends on the size of R5 and C5, and the numerical value given in the figure is about 6 seconds). If the input is high at this time, the output will be output. The other components related to the shaping circuit are C6, which is just a decoupling capacitor and only plays the role of anti-interference.
The next circuit is a distribution circuit composed of CD40 17, which mainly distributes the number of pulses. CD40 17 is actually a decimal counter (triggered by the upper edge, that is, counting a number when the input signal goes from low level to high level), and its output mode is that Q0 outputs a high level when the count is 0; When the count is 1, Q 1 outputs a high level; When the count is 2, Q2 outputs a high level ... and so on, until the output count is 4 (that is, when Q4 outputs a high level), the signal passes through the diode VD 1 into the pin 15 of CD40 17 to make its interior zero, and the count value returns to 0. The remaining components related to the distribution circuit are C7, R6 and VD 1. Among them, VD 1 has been mentioned before, and it plays a switching role here. When the Q4 pin of CD40 17 outputs a low level, the diode is in the reverse off state. At this time, the clearing terminal pulls low through R6 (R6 is also used for C7 discharge when the system is powered off) to make it low. When Q4 outputs a high level, a voltage drop is generated through the diode and R6, so that the clearing pin is at a high level. Because the internal count value of CD40 17 is uncertain when the equipment is powered on, C7 charges instantly when the equipment is powered on, and its instantaneous charging current makes its voltage drop almost zero, that is, CD40 17 realizes the function of power-on reset.
The next circuit is the motor drive circuit. The characteristic of this circuit is that when the distribution signal from CD40 17 is amplified to the base B of the transistor by the current-limiting resistor, the amplified signal from the emitter of the transistor E is finally applied to the control electrode of the triac, so that it can conduct the phase line (live wire, I suddenly remembered the person who answered your question before-why-JNSYCYCYCHY fainted, because this circuit did not protect the isolation device! Anyone who touches any component of this circuit will get an electric shock! ! If you want to trial-produce, I suggest you add an isolation protection circuit, otherwise people will die! )。 In this way, the motor will start to move, and the rotation speed of the motor can be adjusted by changing different electrified phase lines (by "different electrified phase lines" I mean that any one of the three live wires of this motor can be electrified to get different rotation speeds, for example, the rotation speed of the first one is 800 r/min when electrified; When the second root is electrified, the rotating speed is1500r/min; When the third one is energized, the rotation speed is 2200 rpm ... This is because this kind of motor has a special structure. It is recommended to read books on electrical engineering for information. Now, let's explain the related components in this circuit. Three resistors R8, R9 and R 10 are used to limit the current of VT3, VT4 and VT5, and these three transistors are used to provide driving signals to three triacs VS 1, VS2 and VS3 respectively, and also play an amplification role. Finally, the top three LEDs, namely LED 1, LED2 and LED3, should be indicators indicating the current motor speed.
The next part of the circuit is the buzzer circuit, and its core component is IC4(KD-560 12). It is a special voice integrated circuit. When it is powered on and has a trigger signal, the internal local oscillator works and outputs an audio signal through the output pin after special transformation. In this circuit, his trigger signal is provided by the Q 1 pin of CD40 17 (in series). The other related components are: R 1 1 and VDW 1 to form a 5. 1V voltage regulator, which provides normal working voltage for IC4; VT6 and VT7 form a power amplifier circuit to drive speaker B (as can be seen from this power amplifier circuit, the output of this IC4 should be a tone signal, not a voice, otherwise the distortion will be great); Finally, C8, which is the oscillation capacitor of the local oscillator, provides oscillation conditions for the internal oscillation circuit of IC4 (the output audio can be adjusted by changing its size).
The last part is the power supply part of the system. C 1 1 and R 12 form an AC attenuator, VD2 and VD3 form a half-wave rectifier, and IC5, C9 and C 10 form a 9V regulator. After AC power is weakened (to be precise, it should be stepped down), a half-wave rectifier is added for rectification (to keep the polarity of its output unchanged), and finally a stable 9V DC power supply is output through a 9V voltage regulator, which provides normal voltage for the whole system and enables it to work stably.
Please feel free to ask me if there is anything you don't understand.