A simple direction indicator circuit for a bicycle | Using NE555 IC.

How are you all? I hope you are well. By the grace of God, I am also well. Today I am sharing with you a small and useful electronics project, which is a direction indicator circuit for bicycles. I have presented it in a very easy-to-understand step-by-step manner. In this circuit, I have used an NE555 timer and controlled the LED for the left-right indicator. This circuit can be made at home and can be connected to the bicycle very easily.

![Untitled design (2).png] (https://cdn.steemitimages.com/DQmZkSqjH8Zdnyp3SeCw2JMswASUz2MCa6twwoqyW4AkDF8/Untitled%20design%20(2).png)

Edited with Canva.

Functionality of the components used in this diagram.

NE555 Timer IC.

Edited with Canva.

This is a timing chip, which helps to light the LED in a specific rhythm.

SL100 Transistor.

It works like a switch. It controls which side the output will go to in the circuit.

LED red.

Used to show light. Indicates the direction when turning left or right.

SPDT Switch.

The switch helps to select — left or right — which side LED will light.

Electrolytic Capacitor 33 µF.

Keeps the signal inside the circuit stable and creates some delay.

Ceramic Capacitor 0.1 µF.

Works as a light filter and spike removal, so that the circuit works smoothly.

Resistors: 100Ω, 10KΩ, 220Ω.

Controls the current so that the LED or other parts are not damaged.

Step 1: IC pinout.

First, I took all the pins of the NE555 IC. I wrote each PIN number clearly so that it is easy to connect later. I also took a picture with the necessary pen and scale next to it. And I am arranging the pin-out below; which one does what?

Step 2: Power and reset connection.

In the second step, first I gave a 3.7-volt positive line to pin number 8. Then I connected pin number 4 to pin number 8 so that the circuit does not reset while it is on. And I connected pin number 1 to ground.

Step 3: Timing part connection.

Then I placed two 10 kilohm resistors from pin number 7. I also connected the resistors to pins number 6 and 8. Then I placed a capacitor between pins number 6 and 2. This part works to create timing.

Step 4: Output and control connection.

Then I connected a 0.1 microfarad capacitor to pin number 5 so that the circuit works stably. Then I took the output from pin number 3 and used a 220-ohm resistor there.

Step 5: Switch and output control.

Then I connected the output line of pin number 3 to an SPDT switch with a 220-ohm resistor. Through this switch, I can separately select the left and right directions. Then I installed two SL100 transistors on either side — one for the left output, the other for the right output.

Step 6: LED Connections.

Then I installed four 100-ohm resistors across the output of transistor Q1 on the left. Then I connected two red LEDs to each resistor. A total of 8 LEDs were installed.

Step 7: LED Connections on the Right.

Then I installed four 100-ohm resistors across the output of transistor Q2 on the right. Two red LEDs were connected to each resistor. A total of 8 LEDs were installed here as well.

Proof of my hand-drawn circuit.

I took a selfie with my hand-drawn circuit diagram. Below I wrote my username and community name to prove that this is my own work.

Conclusion.

Today I made a direction indicator light for a bicycle. In this circuit, I have used an NE555 timer IC to show left and right direction by flashing an LED. I have made the entire circuit step by step by hand drawing. This is a simple but learning project.

Materials used in this circuit diagram.

Sr. No.	Part name	Value	Quantity
1.	IC	NE555 Timer	1 piece
2.	NPN transistor	SL100	2 pieces
3.	LED	Red color	16 pieces
4.	Switch	SPDT 3 pin selector	1 piece
5.	Electrolytic capacitor	33µF	1 piece
6.	Ceramic capacitor	0.1µF	1
7.	Resistors	100Ω × 8, 10KΩ × 2, 220Ω × 1	Total 11
8.	battery	3.7-volt	1

🟩 Thank you for reading my post and giving your valuable time. Stay well and stay healthy. God bless you. 🟩

Photography Details	📱 Device: Walton Xanon90	📍 Location: Narayanganj, Bangladesh	📷 Captured By: @imranhassan