mini projects

Posted on Feb 4, 2014

This circuit controls the switching of the street light or porch light and it will be automated. This circuit of automatic lamp controller using 7806 regulator IC can be used to automate street lights, tube lights or any other house electrical lightning systems. The IC 7806 is a voltage regulator IC that give a steady output voltage against widely

mini projects
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fluctuating dc input voltage. For this IC, any voltage that appears in common terminal will be reflected at the output. So when the ground terminal is disconnected, the input is available at the output. When the common terminal is connected to the ground, the regulator output is equivalent to the rated voltage, and as soon as the terminal is disconnected from the ground, the output increases up to the input voltage. The common terminal is controlled by a transistor, which works as a switch on the terminal. For automatic control of light, a light-dependent resistor (LDR1) is connected to the base of the transistor. In this way, the voltage regulator is able to operate a light bulb automatically as per the ambient light. To derive the power supply for the circuit, the 50Hz, 230V AC mains is stepped down by transformer X1 to deliver a secondary output of 12V, 250 mA. The secondary output of the transformer is applied to a bridge rectifier comprising diodes D1 through D4, filtered by capacitor C1 and fed to the input terminal of the regulator (IC1). The common terminal (pin 2) of IC1 is connected to the ground line of the circuit through transistor BC557 (T1). The transistor is biased by R2, R3, VR1 and LDR1. The grounding of IC1 is controlled by transistor T1, while light is sensed by LDR1. Using preset VR1, you can adjust the light-sensing level of transistor T1. The output of IC1 is fed to the base of transistor T2 (through...

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