Parking Aids

Car Parking Sonar

Tihs circuit has: automatic switch on on rear gear. led-bargraph display. audible bleep on last led. "good old" design style, no microcontrollers! Based on an ultrasonic amplifier from an article seen on a 1982 magazine, it was once installed on the rear bumper of my Volvo Station Wagon. It served very well for many years. 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. ..

Car Parking helper

A simple but useful circuit for all they have problem with parking car, in spaces without good visibility. The electric circuit appears in picture 1. It is constituted by the IC1 and components round he. When the car bumper touch soft and push lightly the switch S1 then of battery voltage + 9 V it is applied in the circuit, the transistor Q1 turn ON and the diodes D3-4 they blink. After 4 seconds the capacitor C1 charging. The pin 9 of IC1c it goes in high potential, simultaneously the pin 10 goes in low potential and Q1 turn off and the diodes turn off and the circuit it remains in situation of waiting, until the next excitation of switch S1. The consumption in the this stage remains very small, without it aggravates the battery. ..

Ultrasonic Parking controller

A series of five short pulses blasted by the microcontroller only has 5V amplitude, which will be attenuated down to less than 20 mV when received by the receiver circuit. Hence, LM311 voltage comparator was used for signal amplification before transmitting the signal. LM311 was used instead of regular operational amplifier since it has faster switching speed. Low-to-high and high-to-low level output response times were only 115ns and 165ns respectively, which was more than enough for our application since the width of each pulse is 12.5us. The voltage comparator compares the 5V input pulse generated by the MCU to 2.5V. If the voltage level of the input pulse is greater than 2.5V it outputs 12V drawn from the power supply and drives the ultrasonic transducer, otherwise it outputs zero. Hence the 5V input pulses are amplified to 12V pulses. The ultrasonic transducer converts its input voltage into sound waves and emits them at 40kHz frequency...

This circuit was designed as an aid in parking the car near the garage wall when backing up. LED D7 illuminates when bumper-wall distance is about 20 cm., D7+D6 illuminate at about 10 cm. and D7+D6+D5 at about 6 cm. In this manner you are alerted when approaching too close to the wall. All distances mentioned before can vary, depending on infra-red transmitting and receiving LEDs used and are mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device sensitivity...