Table of Contents
we have simply learned about to glow the LED by using SWITCH, now we go ahead to put the automation on it to make it smart.
LED will be ON at darkness and OFF when there is a particular intensity of light in the room, we can adjust at What intensity should LED be on and OFFi
simply we will deal to convert the ANALOG to binary DIGITAL signal output, by comparing analog signal to reference signal.
DEVELOP SMARTNESS TO THE LED
STEP-1 :- Things required
- 9 volt dc power source.
- voltage regulator IC .
- light dependent resister [LDR].
- comparator IC [LM358].
- potentiometer [10k ohm].
- 3mm /5mm led .
- resister [270 ohm, 10k ohm].
- bread board and jumper wires [red,blue,yellow].
- screw driver.
STEP-2 :- Circuit and components connection
- voltage regulator:- 7805 ic which gives the 5-volt output when giving it to +6 volt
- comparator:- LM358 dual comparator ic each comparator compares two variable voltage and gives the output LOW (0) and HIGH (1) voltage.
- potentiometer:- it is a manual variable resistor, it is used to set the reference voltage at the negative terminal of the comparator ic.
- LDR:- (light dependent resister ) its resistance vary according to the intensity of light fall on it, it is used to detect the intensity of light.
STEP-3 :- Implement on bread board
- put all the components on the bread board, as shown in the figure below.
- connect 2nd terminal of the 7805 ic to upper BLUE row and the 3rd terminal connect to RED row of the bread board. [ RED row show +5 volt. with refrence BLUE row that is NEGATIVE row ].
- connect the both upper RED and lower RED rows, and also BLUE to BLUE rows.
- jump the 4th terminal of LM358 to lower BLUE row and 8th pin to upper RED row by using jumper.
- connect the potentiometer 1st and 3rd pin to positive and negative row respectively, 2nd pin connect with the 6th pin of comparator ic by yellow wire.
- one terminal of LDR is connected to the positive row, and second connect with one terminal of resister to PIN 7 and second terminal of 10k ohm resister is connect to the BLUE row.
- connect the resister to the positive row and the positive terminal of the LED
- negative terminal of LED put at the output of the comparator ic [PIN 5]
- check the circuit continuity and also check short circuiting at positive and negative rows by using multimeter.
- if getting continuity at positive and negative than check the connection properly. and don’t connect the battery at this condition.
- finally connect the positive terminal of battery to 1st pin and negative to 2nd pin of the 7805 ic.
- after connect battery, set the potentiometer through screw driver, led may be ON or OFF .
- if led is OFF, at this situation turn the potentiometer at one direction or other until led will turn ON. and than turn pot on reverse direction as it was rotating until at the point where the led get turn OFF.
- if led is ON, than turn the potentiometer at one direction or other until at that point where led is turn OFF.
STEP-4 :- Test the result of the circuit
- after the proper set up we observed that whenever the LDR in darkness than the LED turns on automatically and turns OFF when it goes to under the light.
- we can set, the intensity at which we want to turn the led off and on by rotate potentiometer.