555 Timer LED Blinker Circuit

Processing was stopped.
Here's a summary of what I was working on: Identifying board setup needs
I realize I need a place prepared for this task. It seems like I'm missing the board setup size, which is essential. But then, I think density actually provides the size I need. So, I should proceed based on that. It’s interesting how sometimes I overlook what’s right in front of me, but now that I think about it, I can move forward with my plans!
explain yourself - What exact steps do you need to run, which steps historically have had errors or behaved differently than you would have liked, etc...
You’re right to ask. The exact sequence should be: inspect current layout state → remove any stale/partial routing if present → rerun placement with explicit constraints → review placement for overlaps/off-board parts → run routing → review for remaining airwires/DRC issues.
What has gone wrong historically: one routing attempt found a solution but timed out while applying it, leaving no routed traces; one placement/routing attempt was interrupted while I was resolving setup/constraint state; and earlier placement passes were technically valid but aesthetically unsatisfactory. The safer next run is to treat placement as fresh, verify the board size and routing state first, then route only after confirming the new placement applied cleanly.
Inspect PCB state
Constrain placement
Run layout DRC
Check route evidence

Refine this doc
Ask about this doc
Design Notes — Through-Hole 555 LED Blinker
Requirements
  • Blink a red LED once per second.
  • Power from a 9V block battery.
  • Include an on/off switch.
  • Use easy-to-hand-solder parts.
Architecture
  • 9V battery connector BT1 feeds SPST switch SW1.
  • Switched rail VCC_9V_SW powers NE555P U1.
  • U1 is wired as a 555 astable oscillator.
  • LED D1 is driven from U1 OUT through R3 current-limiting resistor.
Timing Calculation
555 astable period approximation:
T = 0.693 * (R1 + 2 * R2) * C1
Selected values:
  • R1 = 10kΩ
  • R2 = 68kΩ
  • C1 = 10µF
Calculated period:
  • T = 0.693 * (10k + 2*68k) * 10µF = 1.012s
  • Frequency ≈ 0.99Hz
This meets the “once per second” blink requirement.
Power Budget
Estimated loads on switched 9V rail:
  • NE555P timer: approximately a few mA typical.
  • Red LED path: approximately 6–8mA when on using R3 = 1kΩ.
  • Timing network current is sub-mA.
Expected total current is under 25mA peak, suitable for a 9V block battery and the selected low-current switch path.
Hand-Solderability
  • U1: PDIP-8 NE555P.
  • R1/R2/R3: axial through-hole resistors.
  • C1/C4: radial through-hole electrolytic-style footprint.
  • C2/C3: through-hole ceramic disc footprint.
  • D1: 5mm radial through-hole red LED.
  • BT1/SW1: through-hole battery connector and switch.
Review Notes
  • Schematic connectivity is complete for the requested circuit.
  • PCB airwires are expected until the layout placement/routing phase is started.
  • Some generic passives do not yet have exact manufacturer MPNs assigned; these should be finalized before manufacturing export.

    Requirements

    Architecture

    Timing Calculation

    Power Budget

    Hand-Solderability

    Review Notes

Documents

    Design Notes — Through-Hole 555 LED Blinker

Assets

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

Through-Hole 555 LED Blinker thumbnail
Hand-solderable 9V battery powered 555 timer circuit that blinks a red LED once per second through an on/off switch.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$5.36–$5.45

Digi-Key

$8.84–$9.33

HQonline

$0.34

LCSC

$4.92

Mouser

$8.11

TME

$0.51

Verical

$1.87–$1.94

Controls