Car introduction: After successful assembly, the trolley can move forward along the black track with a width of about 15mm. The circuit consists of photoelectric sensing, voltage comparison, and motor drive. The principle is that the reflectivity of the light-emitting tube projected to the black and white parts is different, and the light intensity reflected to the receiving of the photoresistor is different, resulting in a change in the resistance of the photoresistor. LM393 compares the size of the two photoresistors, controls the operation of the motors on both sides, thereby correcting the direction of the car to ensure that the car moves along the black track. Kit parameters: Power supply voltage: 3V (the kit does not contain batteries, you can buy two AA batteries yourself) Board size: 7. 2*10. 5cm Main control chip: LM393 voltage comparator chip, without programming control, LM393 classic application circuit, teaching model Use Reminder: Since many customers have come to ask why only one side of the wheel turns after the trolley is installed, and the LED light on the top side is on, hereby declare that after normal welding and assembly, when it is not on the track, it is normal that only one side of the wheel turns, and the top side on the same side The LED is on, and both LEDs below are on. When walking on the track, the wheels on both sides rotate alternately so that the wiring can be realized. For details, please see the welding production video (to be uploaded). If you want to make your own track, the turn of the track should not be too large. Soldering Tips: The height of the main photoresistor and LED under the front of the car should be moderate, the photoresistor and LED should be parallel, placed on the ground, about 0.2-0.4CM from the ground (you can see the picture if you are not clear), the sensitivity also mainly depends on the welding specification here To what extent. For the installation of the motor gear part, if children have difficulties in installation, you can ask adults to help, and a welding installation video will be released later for your reference. There is a black runway with a width of 15mm on the white field. Our tracking car can drive along the black runway automatically. The reflectivity of white objects and black objects is different. Here we use red LED as the light source. The light is reflected from the ground to the photoresistor. By detecting the change of the resistance of the photoresistor, we can judge whether the car is driving in the white area. If If a black runway is detected, it means that the car is running off track, the motor on this side will slow down or even stop, and the green LED on this side will go out, driving the car to the opposite direction, so that the car can always drive along the track. package includes 1*set of loose parts (not including battery)