PCB Design for Blinking LED
0:03
Work done
- Built the full schematic for the 1 Hz 555 LED Blinker:
- J1 Keystone 967 9V battery connector
- SW1 through-hole SPST on/off switch
- U1 NE555P DIP-8 timer in astable mode
- D1 5 mm red through-hole LED
- R1 = 10kΩ, R2 = 68kΩ, C1 = 10uF timing network
- R3 = 680Ω LED current-limit resistor
- C2 = 100nF VCC decoupling and C3 = 10nF control-pin bypass
- Wired the battery, switch, NE555 astable, LED output, decoupling, and ground connections.
- Set the generic passives to through-hole package formats from the supported Flux package list, including axial resistors, radial timing capacitor, and ceramic disc capacitors.
- Updated the Project Specification document with architecture, values, calculations, layout requirements, and verification plan.
- Simulated the blinker behavior:
- Output frequency: 0.988 Hz
- Period: 1.012 s
- Duty cycle: 53.4%
- LED on-current: 10.36 mA
- Result: meets the ~1 Hz blink target with safe indicator LED current.
- Configured the PCB:
- 50 mm x 50 mm rectangular board
- 2-layer stackup
- 0.5 mm trace width and 0.25 mm clearance/keepout
- Placed all components on the top side with hand-solder-friendly spacing:
- Battery connector near the left edge
- Switch near the top edge
- NE555 and timing parts near the center
- LED near the right edge for visibility
- Auto-routed the board successfully.
- Ran schematic/layout checks:
- ERC: passed
- DRC checks for airwires, overlapping copper, missing footprints, invalid layers, floating copper, and trace corner radius: passed
- ✅ 9V battery connector, on/off switch, NE555 astable circuit, and red LED blinker included.
- ✅ Timing values produce approximately 1 Hz blink rate.
- ✅ Components are through-hole / hand-solder-oriented.
- ✅ PCB is a 50 mm x 50 mm, 2-layer board.
- ✅ Components are placed and routed.
- ✅ ERC/DRC review checks passed with no reported errors.
The design is ready for final human visual inspection and manufacturing export. If you want, I can next generate the manufacturing package: Gerbers, drill files, BOM, and pick-and-place/assembly outputs.
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Project Specification
Project
1 Hz 555 LED Blinker
Goal
Design a fully laid-out, hand-solder-friendly through-hole PCB that blinks a red LED once per second from a 9V block battery through an on/off switch.
Architecture
Diagram
Circuit Choices
- Power input: Keystone 967 through-hole 9V battery snap connector.
- Power switch: C&K L101011MS02Q through-hole SPST switch in series with battery positive.
- Oscillator: Texas Instruments NE555P DIP-8 timer in astable mode.
- Timing values: R1 = 10kΩ, R2 = 68kΩ, C1 = 10uF.
- Estimated frequency: f = 1.44 / ((R1 + 2*R2) * C1) = 1.44 / ((10kΩ + 136kΩ) * 10uF) ≈ 0.986 Hz, meeting the 1 Hz blink requirement within normal component tolerance.
- LED current limit: R3 = 680Ω with a red LED Vf ≈ 2V gives about (9V - 2V) / 680Ω ≈ 10.3 mA when driven high.
- Decoupling: C2 = 100nF across U1 VCC/GND; C3 = 10nF from CONT to GND.
PCB Requirements
- 2-layer PCB.
- Target size: 50 mm x 50 mm.
- Through-hole, hand-solder-friendly spacing.
- Components grouped by power input, oscillator/timing, and LED output.
Verification Plan
- Verify schematic connectivity with ERC review.
- Simulate/analytically verify 555 frequency and LED current.
- Configure 2-layer layout, place components, auto-route traces, then review DRC and airwires.
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