Perfect for beginners learning to solder, this kit includes all the necessary components for building a fully functional photosensitive switch. Designed for students and beginners in electronics, our. nd Technology lessons. The main idea is to use a photoresistance sensor module to detect the ambient light level and, based on this detection, control a relay module. We recommend our 5V USB power supply cable. The delay time can be adjusted on the multi-turn potentiometer R2. The CANADUINO logo on the PCB is the touch. The LDR light sensor is very affordable, but it requires a resistor for wiring, which can make the setup more complex.