I was putting together some LEDs for Halloween and went to calculate the resistor.
Supply voltage 5v. Voltage drop, did not know, but they suggested 4.5 for a white. desired current 15ma equals a 33ohm resistor.
Set it up on a board and am almost blinded when I power it up.
Switch to a 68 ohm and it is still as bright.
The 100 is still no dimmer.
Grab the meter and try to get a ma reading, not used to doing this.
The 100ohm is still reading 20ma.
Play with the calculator and discover the voltage drop is only 3.2v
To get to 10ma I need a 180 ohm resistor.
Oh yea, that 33 ohm I started out with.....
Was pumping out 50ma into a 20ma LED, no wonder it was so bright.