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  • Sonar for Vehicle Parking

  • Created: Feb 26, 2014

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Most of the people that drives a car often find it difficult to park, especially those who are new to driving. The driver’s visibility at the rear portion of the vehicle is not clear, which may result to a car bump. This device helps the driver on backing up a vehicle; it will sense a nearby obstacle and alarm the driver.

This project adopts the concept of sonar (sound navigation and ranging) to identify the distance of an obstacle. An ultrasonic transducer pair is use to transmit ultrasound signal and receive its echo. A series of Inverting Schmitt Trigger (HEF40106BP) is used as an astable multivibrator for transmission, buffer the signal, and boost the voltage span across the ultrasonic transmitter. The ultrasonic receiver detects the echo of the transmitted signal and amplifies the signal through the transistors. The signal is then fed to an Inverting Schmitt Trigger (HEF40106BP) acting as a monostable multivibrator.

The 74HC4017D Johnson decade counter is the core of the system, having ten counter outputs (Q0 to Q9). The first output (Q0) is connected to the transmitter’s side and the nine remaining outputs (Q1 to Q9) to the LED indicators for distance. When the counter starts, the transmitter sends an ultrasonic signal. The echo detected by the receiver triggers the monostable circuit connected at the CP1 pin of the 74HC4017D. When the monostable circuit output goes HIGH, the HEF40106BP pauses the counter with the corresponding LED (distance) indicator ON.

The range of the indicators can be adjusted (suggested distance: 10cm per LED) through another Inverting Schmitt Trigger (HEF40106BP) configured as an astable mutivibrator. It produces a frequency that drives the CLOCK of the HEF40106BP.



This circuit could be very clever or a complete waste of time. But looking at the design, the 4017 outputs Q0 when turned ON and thus the 1k current-limit resistor on the output LEDs has no voltage across it and the voltage divider into the clock of the chip is 1k:100k and thus the clock-line will not go HIGH and the 4017 will not clock. This circuit is just a MESS and you should NEVER draw chips a block but rather as gates and the 4017 should just have all the outputs on one side to make it easy to see what is happening.

Posted: Jun 28, 2014


The project has been updated. You can now check the changes of the diagram and its content.

Posted: Oct 09, 2014



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