Adjust the blinking time of the LED.

by user

In previous data we have put the smartness to our LED by using Light-dependent resistor, now we will learn to make the timmer circuit. by which we can set the ON and OFF time of LED and LED will automatically on and off in a set time by using the potentiometer. and we can operate the 5-volt devices or trigger the high voltage devices for a particular ON and OFF time by using the driver circuit of the devices.

STEP-1 :- Things required 

  •  9 volt dc power source.
  •  voltage regulator ic [7805].
  •  timmer ic  [555-timmer].
  • capacitor [100 uF , 0.1uF].
  • potentiometer [10k ohm].
  • 3mm /5mm led .
  • resister [270 ohm, 10k ohm].
  • breadboard and jumper wires [red, blue,yellow].
  • screwdriver.

STEP-2 : – circuit and components connction

figure 3.1
  • voltage regulator:- 7805 ic which gives the 5-volt output when giving it to +6 volt.
  • 555-timmer:-  it is a multivibrator ic, which is used to generate multiple frequency signals.
  • potentiometer:- it is manual variable resister, it is used to vary the on and off time by varying the charge and discharge time of the capacitor.  
  • capacitor:- on and off time depends on the charge and discharge period of the capacitor which is dependent on the resisters. 
  • ON TIME=  0.61(R + RV
  •  OFF TIME=0.61(R +  RVwhere R  is 10k ohm resister and RV  is potentiometer resister.

See Also : How to Make your own 5v output power bank in 10 min

STEP-3 :- implement on breadboard 

  • put all the components on the breadboard, as  shown in the figure below. 
  • connect the 2nd terminal of the 7805 ic to upper BLUE row and the 3rd terminal connect to RED row of the breadboard. [ RED  row show +5 volt. with reference BLUE row that is NEGATIVE row ]. 
  • connect the both upper RED and lower RED rows, and also BLUE to BLUE rows. they are parallel connected to each other.
  • jump the 1st terminal of 555 ic to lower BLUE  row,  8th  pin to upper RED  row, and also connect the 4th pin to lower RED row by using a jumper. bypass the 5th pin to ground through 0.1uF ceramic capacitor.
  • connect the potentiometer 1st  and 3rd   pin to positive and negative row respectively, 2nd  pin connects with the 7th pin of timmer ic by yellow wire.
  • short the 2nd pin of ic to its 6th pin than connect the capacitor’s ground pin to the negative row and positive to 2nd pin of the ic.   
  • connect the 10k ohm resistor to the 6th and 7th  pin of the ic.
  • put the positive terminal of LED to positive row through 270-ohm resistor, and negative to the output 3rd pin of the ic.  
figure -3.5
  • 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.
  •  we can adjust the on and off time by rotate the potentiometer by screw driver.

STEP-4 :- test the circuit output

  • after connect the battery LED will start to blink with a particular frequency and we can adjust its frequency by rotate the potentiometer.
  • if it is not blink so check your connection properly and also check the output voltage of battery  it must be greater than 6 volt. 

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