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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

About LEAP#9 LEDArduino
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, 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 (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.