This is the circuit diagram of automatic light controller which use 78xx voltage regulator IC series. The voltage regulator ICs deliver a constant output voltage, as against a extensively fluctuating input supply, when the common terminal is grounded. Any voltage about zero volt (ground) interconnected within the common terminal is added to the output voltage. That indicates the enhance in the common terminal voltage is reflected at the output. However, when the common terminal is disconnected from the ground, the maximum input voltage can be obtained at the output.
This characteristic is utilised in the present circuit. When the common terminal is interconnected towards the ground, the regulator output is equivalent to the rated voltage, and when the terminal is disconnected from the ground, the output increases up to the input voltage.
The common terminal is controlled by a transistor, which operates as a switch on the terminal. For automatic control of light, a light-dependent resistor (LDR1) is joined towards the base of the transistor. In this way, the voltage regulator is capable of operate a light bulb automatically as per the ambient light.
For detailed and complete explanation about how this automatic light controller circuit work, you can download the document in PDF version:
This is the circuit diagram of power amplifier 45W using power uPC 1230 as the…
The Horn Circuit This is a basic circuit of car horn and lamp flasher that…
This is the circuit diagram of drinking water alarm based a small water sensor by…
Here is the 200W MOSFET amplifier powered based on four piece of IRFP250N, they are…
This is the 300W RMS stereo power amplifier circuit project. This amplifier is based four…
This is an active stereo tone control circuit using very well known op-amp IC of…