A fully hardware-based Traffic Light Controller designed and simulated in Tinkercad, using 555 Timer ICs to automate the sequential switching of Red, Yellow, and Green LEDs — no microcontroller, no programming required.
This project demonstrates core electronics concepts like astable multivibrator operation, pulse generation, and timing control using only passive and discrete components.
Two 555 Timer ICs are configured in astable mode to generate continuous clock pulses. These pulses drive the LEDs in a timed sequence that mimics a real-world traffic signal:
| Phase | LED | Meaning |
|---|---|---|
| 🔴 Stop | Red | Vehicles stop |
| 🟡 Ready | Yellow | Prepare to move |
| 🟢 Go | Green | Vehicles proceed |
The timing intervals (on/off durations) are set by RC networks (resistors + capacitors) connected to each 555 timer, giving full control over how long each LED stays on — no firmware needed.
| Component | Quantity | Purpose |
|---|---|---|
| 555 Timer IC | 2 | Pulse generation & timing |
| Red LED | 1 | Stop signal |
| Yellow LED | 1 | Caution/ready signal |
| Green LED | 1 | Go signal |
| Resistors | Multiple | Current limiting & RC timing |
| Capacitors | 2 | RC timing network per 555 timer |
| Breadboard | 1 | Prototyping |
| Power Supply (9V) | 1 | Circuit power |
| Connecting Wires | — | Connections |
- Astable Mode — Both 555 timers run continuously, producing a square wave output without any external trigger.
- Sequential LED control — Timer outputs are cascaded/combined so only one LED is active at a time, replicating real traffic light phasing.
- No microcontroller — Pure analog/digital logic via ICs and passive components.
Designed and simulated using [Tinkercad]
You can fork and run the simulation directly in Tinkercad to observe the LED sequencing in real time.
The breadboard layout includes:
- Power rails (red/blue) feeding both 555 ICs
- RC networks on each timer for independent timing
- LED outputs with current-limiting resistors
- Cross-connections between timer stages for phase sequencing
- 555 Timer IC in astable configuration
- RC time constant and frequency calculations
- Pulse width modulation basics
- Sequential logic without a processor
- Practical traffic signal automation
- Open Tinkercad
- Import or recreate the circuit from the schematic
- Click Start Simulation to watch the LEDs cycle
- Gather all components listed above
- Assemble on a breadboard following the circuit diagram
- Power with a 9V battery or DC supply
- Adjust R/C values to change timing durations
Garimaa Das
- Built using Tinkercad
- No Arduino. No code. Pure hardware logic.
"The best code is no code at all." — This project takes that literally.