The Light Sensor is a very simple to use , but very versatile, addition to any control and automation system. Wherever there is a need to obtain a measure of brightness / ambient light, this device can be the perfect solution. It is based on a Light Dependant Resistor (LDR) which protrudes from the front edge of the board allowing it's support board and associated electronics to be discretely mounted with just the LDR showing. It has a simple 3 point connection header and requires 5v DC to operate. Since it only requires a small current, the external 5v is very often derived from a convenient USB port or similar. The output provides an analogue voltage in the range 0 to +5v proportional to the brightness of the light detected. The brighter it is, the lower the voltage and vice-versa.