Introduction: AUTOMATIC LIGHT ON/OFF CONTROL USING TIMER

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COMPONENT LIST
AT89C2051       
LM7805       
DIODE        
RELAY
CRYSTAL OSCILLATOR
COMMON ANODE SEVEN SEGMENT DISPLAY
TRANSFORMER
BC547 TRANSISTOR
BC557 TRANSISTOR





PROJECT SPECIFICATION

4 Digit 7 Segment 24 hours Clock Timer Is Use For Control Any Application. You Can Program Both On Time & Off Time Through This Project. It Require only 3v Battery Back Up. Is Suitable For Switching Loads Upto 500W.The circuit is controlled by a AT89c2051 micro controller. This drives the relay, which switches the mains voltage from the input connector k1 to the output connector K2, and they’re by turns on the load. The 7-segment display shows the time.

Step 1: AUTOMATIC LIGHT ON/OFF CONTROL USING TIMER

BLOCK DIAGRAM

For power supply to circuit we use bridge rectifier in which we use transformer,   4 diode and regulator IC’s LM7805
A circuit diagram of the clock timer,P1.0-P1.7 drives 7-segment common anode LED display with sink current.

P3.0-P3.3 also drives a base pin of 4-PNP transistor, BC557 with sink current.

As shown in the figure, the 2nd 2-digit LED that connected to P3.2 and P3.3 is rotated 180 degrees to the 1st 2-digit allowing the pt. segment to be used for 1 second blinking.

P3.0-P3.3 also connects four momentary switches while the other legs are tied to input port P3.4.

During display and key switch scanning, a logic '0' is shifted from P3.0 to P3.3,

If there was a key pressed,

P3.4 then became low.

P3.7 is a 1-bit sink current driving;

A BC547 to drive a small electromechanical 12V.


TECHNICAL SPECIFICATION

Display type - 4 Digit 7 Segment LED Display
Operating voltage - 230V AC
Max. Timing setting - 24hour(only for hours & minutes)
Battery back up – 3.6V only (1.5V x 3)
Output load - 230V AC

Step 2: AUTOMATIC LIGHT ON/OFF CONTROL USING TIMER

Step 1:- When we power on the supply it given the time 00:00.
(we are using battery backup so we don’t get this value on the circuit )
Step 2:- by the 1st switch which is for the hour set.
Step 3:- by the 2st switch which is for the Min set.
Step 4:-if we use as on or off then set 4th number switch which is on or off the relay.
Step 5:- after set all the time we press 3rd switch which set the on time and set the off time.