Transistor Based LED Alternator Blinker Circuit

This circuit is for simple Transistor Based LED Alternator Blinker Circuit; here, two LEDs blink one after another as this circuit uses two NPN transistors.

This circuit is an astable multivibrator, also known as an oscillator circuit; also this project is ideal for beginners because it helps them learn transistor switching, and we can further, use it in toys, indicators and decorative applications.

Circuit Working:

Parts List:

Components	Values	Quantity
Resistors	1k , 100k	2 each
Capacitors	Electrolytic 10uF 25V	2
	Electrolytic 100uF 25V	1
Semiconductors	Transistors BC547	2
	LEDs any color 5mm	2
	Power Supply 12V Battery	1

This circuit works like astable multivibrator as there is no stable condition in this circuit.

When power supply is ON then one transistor is ON first; assume Q1 becomes ON and then LED1 will glow and then Q2 stays OFF at that time and so LED2 will not glow.

Now capacitor C1 starts charging through resistor R2 and after some time when C1 gets full then C1 discharges and then this discharge makes Q1 OFF.

At the same time when Q2 becomes ON then LED2 will glow and LED1 will go OFF and now capacitor C2 starts charging and after some time C2 also discharges.

Therefore, same action repeats again and again, because of this the LEDs blink one by one.

Formula with Calculation:

Time delay formula:

T = 0.69 × R × C

where,

• R is resistance in ohms
• C is capacitance in farads

For R = 100K and C = 10uF T = 0.69 × 100000 × 0.00001 T = 0.69 seconds

Total blinking time for one full cycle: total time = 2 × T

Total time = 1.38 seconds

We can change the blinking speed by increasing the capacitor value for slower blinking or decreasing the capacitor value for faster blinking.

How to Build:

To build a Transistor Based LED Alternator Blinker Circuit follow the below steps:

• First, take all the parts as shown in circuit diagram.
• Next, transistor Q1 emitter goes to ground, collector of Q1 connects to LED1 cathode and anode to resistor R1 and base of Q1 connects to R2 and C2.
• Then transistor Q2 emitter goes to ground, collector of Q2 connects to LED2 cathode and anode to resistor R4 and base of Q2 connects to R3 and C1.
• After that, capacitor C1 positive connects between Q1 collector and LED1 cathode.
• Now C1 negative goes to Q2 base and C2 positive connects between Q2 collector and LED2 cathode and also C2 negative goes to Q1 base.
• Finally, battery positive goes to positive supply line and battery negative goes to common ground line.

Conclusion:

Overall, this is a simple and useful Transistor Based LED Alternator Blinker Circuit, it uses minimum components and is easy to understand and build.

Also, we can easily adjust the blinking speed, and this circuit clearly demonstrates transistor switching, making it ideal for students and beginners.