Hii friend,

Today I am going to make a circuit of traffic light.This circuit I will make using BC547 Transistors.

Let's get started,

Step 1: Take All Components As Shown Below

Components required -

(1.) Transistor - BC547 x3

(2.) Resistor - 1K x3

(3.) Resistor - 100K x2

(4.) Resistor - 33K x1

(5.) Red LED - 3V x2

(6.) Yellow LED - 3V x2

(7.) Green LED - 3V x2

(8.) Capacitor - 25V 470uf x2

(9.) Capacitor - 25V 100uf x1

(10.) Battery - 9V x1

(11.) Battery clipper x1

Step 2: Fold Pins of Transistors Like This

As pins are folded in the picture like that we have to fold.

Step 3: Connect Red LED to Transistor

Solder +ve legs of Both Red LED to Collector pin of a Transistor.

Step 4: Connect Green LED to Transistor

Solder +ve legs of Both Green LEDs to Collector pin of 2nd Transistor.

Step 5: Connect Yellow LED to Transistor

Solder +ve legs of Both Yellow LED to Collector pin of 3rd Transistor as solder in the picture.

Step 6: Connect Emmiter of Transistors

Next we have to connect emmiter pins of all transistors and -ve legs of all LEDs (Red, Green and Yellow) to each other as you can see in the picture.

Step 7: Connect 1K Resistors

Next Connect 1K resistors to the Collector pins of all transistors as solder in the picture.

Step 8: Connect 100K Resistors

Next solder 100K resistors to the Base pin of Green and Red LED Transistor as you can see in the picture.

Step 9: Connect 33K Resistor

Solder 33K resistor to the Base pin of Yellow LED Transistor as solder in picture.

Step 10: Connect Out Wires of All Resistors

Next we have to solder Out wires of all Resistors as you can see in the picture.

Step 11: Connect 100uf Capacitor

Next solder +ve pin of 100uf capacitor to Base pin of Yellow LED Transistor and Solder -ve pin to Collector pin of Red LED Transistor as you can see in the picture.

Step 12: Connect 470uf Capacitors

[Capacitor 1] - Next connect +ve pin of 470uf capacitor to Base pin of Green LED and solder -ve pin to Collector pin of Yellow LED as solder in the picture.

[Capacitor 2] - Solder -ve pin of 2nd 470uf capacitor to Collector pin of Green LED Transistor.

Step 13: Connect +ve Pin of 2nd 470uf Capacitor

Solder +ve pin of 2nd 470uf Capacitor to Base Pin of Red LED Transistor using a wire as you can see in the picture.

Step 14: Connect Battery Clipper Wire

Solder +ve wire of battery clipper to Out wires of all resistors and -ve wire to common emmiter pins of transistors and -ve legs of LEDs as connected in the picture.