What You'll Build
A classic LED flasher circuit that blinks an LED on and off automatically using the 555 timer IC. This is the perfect beginner project!
Parts List
| Component | Quantity | Value |
|---|---|---|
| 555 Timer IC | 1 | NE555 |
| Resistor R1 | 1 | 10KΩ |
| Resistor R2 | 1 | 100KΩ |
| Capacitor C1 | 1 | 10µF |
| Capacitor C2 | 1 | 0.01µF |
| LED | 1 | Any color |
| Resistor R3 | 1 | 470Ω |
| Battery | 1 | 9V |
| Breadboard | 1 | - |
| Jumper wires | Several | - |
Understanding the 555 Timer
The 555 timer is one of the most popular ICs ever made. In astable mode, it produces a continuous square wave — perfect for blinking LEDs.
Pin Configuration
Pin 1 - GND
Pin 2 - Trigger
Pin 3 - Output
Pin 4 - Reset
Pin 5 - Control
Pin 6 - Threshold
Pin 7 - Discharge
Pin 8 - VCC
Step-by-Step Instructions
Step 1: Place the 555 IC
Insert the 555 timer IC across the center gap of your breadboard.
Step 2: Power connections
- Connect Pin 8 to positive rail (VCC)
- Connect Pin 1 to negative rail (GND)
Step 3: Connect R1
Connect a 10KΩ resistor between Pin 8 (VCC) and Pin 7 (Discharge).
Step 4: Connect R2
Connect a 100KΩ resistor between Pin 7 (Discharge) and Pin 6/2 (Threshold/Trigger).
Step 5: Connect C1
Connect 10µF capacitor between Pin 6/2 and GND. Mind the polarity! (+ goes to Pin 6).
Step 6: Reset and Control
- Connect Pin 4 (Reset) to VCC
- Connect a 0.01µF capacitor between Pin 5 and GND
Step 7: Output LED
Connect a 470Ω resistor to Pin 3, then an LED to GND.
Step 8: Power Up!
Connect your 9V battery and watch the LED blink!
Calculating Blink Rate
Frequency = 1.44 / ((R1 + 2×R2) × C1)
f = 1.44 / ((10K + 200K) × 10µF)
f ≈ 0.68 Hz (about 1 blink per 1.5 seconds)
Experiment by changing R2 or C1 values to change the speed!
Troubleshooting
- LED not blinking? Check IC orientation (look for the notch on Pin 1 side)
- LED stays on? Check C1 polarity
- Nothing works? Verify battery connection and voltage (should be 5-15V)
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