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.
