The assembly steps Step 1 Welding circuitElectric welding part is simpler welding sequence according to the principle of component level from low to high the first welding eight resistance is important to use multimeter to confirm resistance is correct D4 D5 R13 R14 can temporarily not welding integrated circuit chips can temporarily not insertedStep 2 Mechanical assemblyThe red line is connected to the 3V positive power supply the yellow line grounding excess wire can be used for motor wire Step 3 The installation of a photoelectric circuitPhotosensitive resistance and light emitting diodes note polarity is reverse mounted on the PCB and the ground distance is about 5 mm both photosensitive resistance and light emitting diodes are 5 mm distance Finally you can power test Step 4 Vehicle debuggingThe right direction is along the universal wheel direction if you press and hold the left photoresistor the wheels on the right side of the car should be rotated Press and hold the right photoresistor the wheels on the left side of the car should be rotated if the car driving back can also exchange the wiring of two motors if the one side normal and the other side back up as long as you can swap wiring of back side Note We dont supply any manuals please note about this befor you buy it Package included 3 x Electronic DIY Kit batteries are not included