Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Good old parking sonar

Good old  parking sonar

It is an ultrasonic parking sonar. Connecting it to the reverse gear lights, it switches on automatically and shows you the distance to the nearest obstacle (according to his beam) on a led scale. When the last led lights, a buzzer is also activated telling you to stop immediately.
It works on the sonar principle, sending an ultrasound burst and listening for first echo. The burst generated by the oscillator built around U4D (you must set the frequency using TR2 to have 40 kHz or the maximum sensitivity), U4E buffers the output and U4F boost the signal doubling the voltage span across the TX piezo transducer .

A new burst is generated each time the decade counter (4017 in the circuit diagram) is in its reset state, that is output 0 is selected. The other outputs (1 to 9) are scanned sequentially following burst generation, until an echo strikes back the RX receiver. It is then amplified by the transistor input stage, triggering the monostable built around U4A – U4B. The monostable stops temporarily the scanning, and a led corresponding to the obstacle distance appears as continuously lit. The buzzer bleeps when the first led (minimum distance) il lit.

When the monostable expires, scanning is resumed and restarting the send-and-listen sequence. If no echo is received, the scanning never stops and all the leds are slightly lit.

I enjoyed the sonar for many years. It was installed below the car’s rear bumper in a plastic case. Do not choose an enclosure too small: always separate the transducers by 7-10 cm and plenty of sound-absorbing material, otherwise the receiver will reveal the direct sound instead of the reflected one. The same applies if the sound travels through a rigid fixture, so it is a good idea to fix them with separated supports.
And remember not to mount the transducers exposed to direct sunlight nor rain.

Visit Here for more.

 

More Articles to Read

A 3D-printed e-drum pad
A 3D-printed e-drum pad
Interactive geodesic LED dome = extreme geometric fun!
Interactive geodesic LED dome = extreme geometric fun!
Guide to build your 3.3v power supply
Guide to build your 3.3v power supply
SDR radio breathes life into a 75 year old Marconi CR100
SDR radio breathes life into a 75 year old Marconi CR100
A Time for Ranting!
A Time for Ranting!
Emulate a Commodore 64 keyboard with a modern PC and an Arduino
Emulate a Commodore 64 keyboard with a modern PC and an Arduino
USB2005 and USB97C202 Sharing ATA/ATAPI Drive w/ Another Controller
USB2005 and USB97C202 Sharing ATA/ATAPI Drive w/ Another Controller
Robotic Cat Laser
Robotic Cat Laser
LED traffic light
LED traffic light
Estimating Power for ADSP-BF561 Blackfin® Processors
Estimating Power for ADSP-BF561 Blackfin® Processors

Top




Shares