Automatic night lamps circuit serves to control the lights at night automatically. Automatic lamps can be lit at night, such as garden lights, street lights and more. The lamps can be turned on automatically at night, because it is controlled using a circuit that can distinguish day and night, one of the circuit examples that can be used to automatically control the night light is an automatic night light the circuit as shown below.
Automatic Night lamps circuit
Automatic night circuit on the image above is the application of a photo transistor is used as a light sensor. Photo transistor in the circuit of the lamp is automatically set to sense light, which at low light intensity (night) it will provide forward bias the transistor to activate the relay. When the intensity of light received by photo transistor will not provide forward bias to the transistor, so that the relay is energized and is in the Off condition. In the circuit above the nightlight automatically comes with a reverse diode mounted on the source voltage relays, it aims to prevent backflow from the induction coil relays in the event of changing conditions in the relay.
Setting Automatic Lamps Circuit
In the circuit of the automatic lamps on the variable resistor VR1 is equipped with a function to adjust the sensitivity of the exposure on the photo transistor. VR1 so that in principle and serves to set the time or the extinction of light-controlled lighting.
Automatic night lamp circuit above takes 9 Volt DC voltage source and can be used to control a DC lamps or 220 V AC lamps, this is because the system is switching lamps (load) using relays.