It is focusing the beam on a light dependent resistor to the right which looks almost like a red LED due to the intensity of the light. The simplicity of this circuit is fascinating. On the ...

This transistor switching circuit uses a mosfet transistor, a voltage divider (consisting of a \(5 kΩ\) resistor and an LDR) and a \(5 ... is on or off at light levels of 10 lux and 1000 lux ...