I constantly see people on Reddit /r/ece, /r/electronics, etc asking for advice on how to drive LEDs. It happens at least once a week. The classic approach is to take the input voltage, subtract the LED's forward voltage, and then use V = IR to compute the appropriate resistor. And that does work.
( But there's another way. In my opinion, a better way.Collapse )
Here it is:
Click on the image to open circuit simulation in a new window/tab. (NOTE: Requires Java capable browser.)
Simple, no? The only thing you need to know is how to calculate the resistor. Here's the formula:
Rbase = 100 * ((Vconstant - 0.65) / Iconstant)
( Read more...Collapse )