LED Blinker Circuit Design

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Running 8 design checks.
Started: running final validation and completion.

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Work done
  • Verified the existing 9 V battery blinker schematic is complete and matches the plan: J1 battery input, SW1 power switch, U1 NE555 astable, R1 + R2 + C2 timing network, R3 current limit, LED1 red LED, plus C1 supply decoupling and C3 control-voltage bypass
  • Renamed the project to 9V 555 LED Blinker and updated the description to reflect the finished design
  • Confirmed the selected timing values produce approximately 0.988 Hz, which is effectively the requested 1 Hz blink rate
  • Updated the Design Notes document with the architecture, timing calculation, LED current estimate, and hand-soldering rationale
Success criteria review
  • ✅ The circuit blinks a red LED at approximately 1 Hz using U1 in astable mode
  • ✅ SW1 is placed in series with the battery positive path to control power to the whole circuit
  • ✅ The parts are hand-solder friendly: PDIP-8 U1, through-hole J1, through-hole SW1, axial resistors, radial/disc capacitors, and a 5 mm THT LED1
Next steps I can continue to PCB layout next by sizing the board, selecting a Standard 2 Layer stackup, and placing the through-hole parts for easy assembly. I can also simulate the oscillator and LED current if you want an extra verification pass before layout.
Place the PCB
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Design Notes
9V LED Blinker
Architecture
  • 9V battery clip input
  • SPST on/off switch in series with battery positive
  • NE555 timer in astable mode
  • Red 5 mm LED driven from 555 output through series resistor
  • Through-hole / hand-solder-friendly parts throughout
Timing Selection
Using the standard 555 astable equation:
f=1.44(RA+2RB)Cf = \frac{1.44}{(R_A + 2R_B)C}
Selected values:
  • $R_A = 68k$
  • $R_B = 39k$
  • $C = 10uF$
Calculated frequency:
  • $f \approx 0.988 Hz$
This is effectively a 1 Hz blink rate and uses easy-to-source through-hole values.
LED Current Limit
Selected series resistor:
  • $R_{LED} = 680\Omega$
At 9V supply and approximately 2V red LED drop, the current is roughly:
  • $(9V - 2V) / 680\Omega \approx 10.3mA$
This is bright enough for indication while remaining safe for a standard 5 mm red LED and easy for a 555 output to drive.
Practical Build Choices
  • NE555 in PDIP-8 for easy hand soldering
  • Through-hole 9V battery snap connector
  • Through-hole SPST slide switch
  • Axial resistors
  • Radial electrolytic timing capacitor
  • 100nF supply decoupling capacitor across VCC and GND near the 555

    9V LED Blinker

    Timing Selection

    LED Current Limit

    Practical Build Choices

Documents

    design-notes

Assets

Assets are files uploaded to this project which can be used in various ways.

9V 555 LED Blinker thumbnail
Simple hand-solderable 9V battery LED blinker using a NE555 astable oscillator, on/off switch, battery snap connector, supply decoupling, and a red status LED blinking at approximately 1 Hz.

Properties

Properties describe core aspects of the project.

Pricing & Availability

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