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Project Notes

#009 Blink

The most basic LED blinking circuit.


There’s not much to note in this circuit other than it is a good test that everything is working OK. Pin 13 has an LED connected on most Arduino boards, so the off-board LED is optional.

I thought I’d measure the electritcal characteristics with various resistors and a Red LED. My Arduino is supplying 4.98V on the digital GPIO pin when taken high and measured without load. Here are the figures under load:

R1nom R1act Vr Vl V mA
220R 218R 2.69 1.95 4.65 11.5
1kR 989R 3.04 1.85 4.90 3.0
10kR 9.86kR 3.22 1.73 4.96 0.32
  • Vr = voltage drop over resistor
  • Vl = voltage drop over LED
  • V = voltage drop over resistor + LED
  • mA = current

It seems the current is a little lower than theoretical I guess that’s the accuracy and the affect of my multimeter on the circuit when doing the current measurement.


The Breadboard

The Schematic

The Build

Credits and References

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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.