Blinking led

555 Timer LED Blinker

A simple LED blinker circuit built around the NE555P timer IC, designed as a complete PCB project in KiCad — from schematic capture through to manufacturing-ready Gerber files.

Overview

This is a classic astable (self-triggering) 555 timer circuit that blinks an LED on and off at a fixed rate. It was built as a first hands-on project to learn the full PCB design workflow: schematic design, component selection, electrical rule checking, PCB layout, and generating files for fabrication.

Components Used

Component Value / Part Function

U1 NE555P Timer IC, configured in astable mode to generate the blink signal

R1 10kΩ Resistor Timing resistor

R2 1kΩ Resistor Timing resistor

C1 0.01µF Ceramic Capacitor Stabilizing capacitor (pin 5, CV)

C2 10µF Electrolytic Capacitor Timing capacitor (sets the blink rate)

R3 220Ω Resistor LED current-limiting resistor

D1 LED Visual blink output

TP1 Test Point (battery) Power input connection point

How It Works

Power: The circuit is powered through a test point (TP1), standing in for a 9V battery connection — VCC and GND rails feed the 555 timer.

Timing network: R1 and R2 are connected to the DISCHARGE (pin 7) and THRESHOLD (pin 6) pins, with C2 (10µF) forming the RC timing loop that sets how fast the circuit charges and discharges. This combination directly controls the blink rate.

Stabilizing capacitor: C1 (0.01µF) sits on the CONTROL VOLTAGE pin (pin 5) to ground, keeping the timer's internal reference voltage stable and preventing erratic triggering.

Output: Pin 3 (OUTPUT) switches HIGH and LOW at the timing rate set by R1, R2, and C2. This output drives R3, which limits current to the LED (D1), making it blink on and off.

Reset: Pin 4 (RESET) is tied to VCC to keep the timer continuously enabled.

Design Process

Schematic captured in KiCad, with all components wired according to the standard 555 astable configuration.

Verified using KiCad's Electrical Rules Checker (ERC).

PCB layout completed with component placement and routing.

Gerber files generated for manufacturing.

Files Included

.kicad_sch — Schematic source file .kicad_pcb — PCB layout file .kicad_pro — KiCad project file Gerber files — Ready for PCB manufacturing

Tools Used

KiCad — schematic capture, PCB layout, and Gerber generation Status

Design complete. First hands-on PCB design project, built to learn the end-to-end KiCad workflow.