One of the 40kHZ ultrasonic transmitting circuits. The output of the F1~F3 three-gate oscillator at F3 is a 40kHZ square wave. The operating frequency is mainly determined by C1, R1 and RP. The RP adjustable resistor is used to adjust the frequency. . The output of F3 excites one end of the transducer T40-16 and the inverter F4, and the output of F4 excites the other end of the transducer T40-16. Therefore, adding F4 doubles the excitation voltage. Capacitors C3 and C2 balance the outputs of F3 and F4 to stabilize the waveform. The inverters F1~F4 in the circuit use four of the six CC4069 inverters, and the remaining two are not used (the input end should be grounded). The power supply uses a 9V laminated battery. The measured F3 output frequency should be 40kHZ±2kHZ, otherwise RP should be adjusted. Transmitting ultrasonic signals is greater than 8m.
40kHZ ultrasonic transmitter circuit 2. The transistors VT1 and VT2 in the circuit form a strong feedback stable frequency oscillator. The oscillation frequency is equal to the maximum oscillation frequency of the ultrasonic transducer T40-16. T40-16 is a feedback coupling element and an output transducer for the circuit. The oscillation waveform at both ends of T40-16 is similar to a square wave, and the voltage amplitude is close to the power supply voltage. S is the power switch. Press S once to drive T40-16 to emit a series of 40kHZ ultrasonic signals. The working voltage of the circuit is 9V, and the working current is about 25mA. Transmitting ultrasonic signals is greater than 8m. The circuit works without debugging.
The third 40kHZ ultrasonic transmitter circuit consists of VT1 and VT2 as a positive feedback oscillator. The oscillation frequency of the circuit is determined by the T40-16 of the feedback component, and its resonant frequency is 40kHZ±2kHZ. The frequency stability is good and does not require any adjustment. The T40-16 is used as the transducer to emit a 40kHZ ultrasonic signal. Inductor L1 and capacitor C2 are tuned to resonate at 40kHz. This circuit adapts to a wide range of voltages (3~12V), and the frequency remains unchanged. The inductor is fixed and has an inductance of 5.1mH. The working current of the whole machine is about 25mA. Transmitting ultrasonic signals is greater than 8m.
The fourth 40kHZ ultrasonic transmitter circuit, which mainly uses a four-NAND gate circuit CC4011 to complete the oscillation and driving functions, radiates ultrasonic waves through the ultrasonic transducer T40-16 to control the receiver. Gate YF1 and gate YF2 form a controllable oscillator. When S is pressed, the oscillator starts to vibrate. Adjust RP to change the oscillation frequency, which should be 40kHZ. The oscillation signal controls the operation of the differential phase driver composed of YF4 and YF3 respectively. When YF3 outputs high level, YF4 must output low level; when YF3 outputs low level, YF4 outputs high level. This level controls the T40-16 transducer to emit 40kHZ ultrasonic waves. In the circuit, YF1~YF4 adopts the high-speed CMOS circuit 74HC00 four-NAND gate circuit. This circuit is characterized by large output drive current (greater than 15mA) and high efficiency. The working voltage of the circuit is 9V, the working current is greater than 35mA, and the ultrasonic signal emitted is greater than 10m.