Скачать или смотреть Photo Resistor LED Circuit on Arduino

This circuit will turn on an LED when the light being received by the photoresistor drops below a certain level. The LED will turn off when the light received by the photoresistor is above a certain level. The photoresistor is placed in a series circuit with a 10k ohm resistor with a wire in between the resistor and photoresistor that is connected to the Arduino on pin A0. This creates a voltage divider circuit and varying voltage is created by the photoresistors reaction to light: increased resistance when exposed to a higher level of light and decreased resistance when exposed to lower levels of light. The formula for the voltage dropped across the photoresistor is Voltage(photo) = Voltage(total) x Resistance(photo)/Resistance(total) with voltage in volts and resistance in ohms. So when the light source is removed from the photoresistor then the resistance through the photoresistor is dropped as well which in turns drops the voltage dropped across it. This drop is then read by the Arduino and it sends a "High" signal of 5 volts to the LED. And vice-versa for increasing light received by the photoresistor.