MA40A3 with two ultrasonic parking sensor distance sensor circuit settings VR1, VR2 potentiometer can do this with a direct 12-volt car battery from the circuit can work with buzzer provides audible warning Ultrasonic Analog Parking Sensor Project sorce http://www.siliconchip.com.au/cms/A_102713/article.html... Electronics Projects, MA40A3R Ultrasonic Parking Sensor Circuit (analog desing) "analog circuits projects, " Date 2019/08/02