I have a two series circuit with two leds rated 3.20-3.5 with max current 20ma on a 9v power supply. so a total of four leds in two series with a 100Ω resistor on each, which should bring current down to 20ma but when I test forward voltage across each led I'm getting between 4.2-4.5 volts on all leds. I've tested the resistors and both are showing about 100-102Ω. What would cause this other than a bad resistor. I've also tried swapping out the 100Ω resistors with 220Ω resistors with same result.
-
Categories
-
Platforms
-
Content