| 摘要 |
The circuit for detecting the rear obstacle with an ultrasonic, such as turning on the LED corresponding to the safe, watch, or danger state as well as announcing with the synthesized voice, includes a reference timing circuit (1), an oscillator (2), transmitters (3,3'), receivers (4,4'), amplifiers (5,5'), rectifiers (6,6'), distance calculators (7,7') for calculating the distance from the obstacle with the time difference of the reflected ultrasonic wave, LEDs (10), a ramp voltage generator (21), an analog switch (22), a sample and hold circuit (23), a voice synthesizer (24), an amplifier, and a speaker (26).
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