LED Blinking Circuit Design

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Project Specification

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Hand-solderable 9V battery powered red LED blinker using a DIP-8 NE555 timer in astable mode. The LED blinks approximately once per second a...

Board Bring-Up Plan

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Inspect solder joints, especially BT1, SW1, U1, C1 polarity, D1 polarity, and the axial resistors. Confirm C1 positive lead is connected to ...

flux

Built the schematic for a hand-solderable 9V NE555 red LED blinker and renamed the project 1 Hz 555 LED Blinker. It uses a 9V battery holder, SPST slide switch, DIP-8 NE555, through-hole LED, axial resistors, and leaded capacitors; ERC/review checks show no open warnings or errors.
Open items:
  • PCB placement/routing has not been done yet.
  • Blink rate is nominally ~0.99 Hz; electrolytic capacitor tolerance will shift the exact timing.
Docs created:
Suggested next steps:
  1. Place the through-hole parts on a simple PCB.
  2. Route the board.
  3. Add silkscreen labels for battery polarity, switch ON direction, LED polarity, and 555 orientation.
Place route review
Place the PCB
Route the board
Add silkscreen labels
Run layout checks
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Files

Schematic

Layout

Preview

U1
BT1
R2
Resistance
68kΩ
R3
Resistance
680Ω
R1
Resistance
10kΩ
C2
Capacitance
0.1uF
C1
Capacitance
10uF
SW1
D1
C3
Capacitance
0.01uF
Project Specification
Overview
Hand-solderable 9V battery powered red LED blinker using a DIP-8 NE555 timer in astable mode. The LED blinks approximately once per second and power is controlled with a through-hole SPST slide switch.
Requirements
  • Power source: 9V PP3/block battery.
  • User control: on/off switch in series with battery positive.
  • Output: red LED blink indicator.
  • Blink rate: approximately 1 Hz / once per second.
  • Assembly: prioritize through-hole, hand-solderable components.
Circuit Topology
  • BT1: BH9VPC 9V battery holder.
  • SW1: AS11CH SPST through-hole slide switch.
  • U1: NE555P DIP-8 timer powered from switched 9V.
  • R1 = 10 kΩ from V9_SW to DISCH.
  • R2 = 68 kΩ from DISCH to TRIG/THRES.
  • C1 = 10 µF from TRIG/THRES to GND, positive on timing node.
  • C2 = 0.1 µF from V9_SW to GND near U1.
  • C3 = 0.01 µF from CONT to GND.
  • R3 = 680 Ω in series with red LED D1 from U1 OUT to GND.
Timing Estimate
For a 555 astable:
  • t_high = 0.693 × (R1 + R2) × C1
  • t_low = 0.693 × R2 × C1
  • period = 0.693 × (R1 + 2R2) × C1
With R1 = 10 kΩ, R2 = 68 kΩ, C1 = 10 µF:
  • t_high ≈ 0.54 s
  • t_low ≈ 0.47 s
  • period ≈ 1.01 s
  • frequency ≈ 0.99 Hz
Electrolytic tolerance will affect the exact blink rate, but it should visibly blink about once per second.
Validation Criteria
  • U1 VCC and RESET tied to switched 9V.
  • U1 GND tied to battery negative.
  • TRIG and THRES tied together at the C1 timing node.
  • DISCH connected between R1 and R2.
  • CONT bypassed to GND with 10 nF.
  • Output drives red LED through a current-limiting resistor.
  • ERC has no open errors/warnings for the checked schematic rules.

  • Overview

  • Requirements

  • Circuit Topology

  • Timing Estimate

  • Validation Criteria