Hardware circuit diagram of ultrasonic range finder

AT 89C2051 outputs a pulse group of 10 pulses with a pulse width of 250μs and a carrier wave of 40kHz through the external pin P1.6. It is added to the primary of the transformer in push-pull form, and the ultrasonic transducer is driven to emit through boost conversion. While transmitting, P1.7 outputs a high level to start, charging capacitor C4. At the end of the transmission, the high level flips to low level, and C4 begins to discharge the voltage divider composed of R2 and R3 and output it to the negative terminal of the comparator. The ultrasonic receiving transducer sends the received ultrasonic waves reflected by obstacles to the amplifier for amplification. This is a high-gain, low-noise amplifier. After detecting the amplified signal, the detected echo is sent to the positive input of the comparator. end. The level of P1.7 output during transmission can inhibit the flipping of the comparator, thus inhibiting the ultrasonic wave emitted by the transmitter from directly radiating to the receiver and causing false detection.