I built a test light using A resistor and LED in series.
The total voltage is 74 DC volt, the resistor is 3900 ohm.
Current calculates at .0189.
LED's are rated at 30 ma and 3.2 to 3.8 volts.
My LED's work for a short time then burn out. Can anyone
explane to me why and what I need to do to correct this problem.
I built a test light using A resistor and LED in series.
The total voltage is 74 DC volt, the resistor is 3900 ohm.
Current calculates at .0189.
LED's are rated at 30 ma and 3.2 to 3.8 volts.
My LED's work for a short time then burn out. Can anyone
explane to me why and what I need to do to correct this problem.
Make sure that the resistance is 3.9K by checking with a meter. I have seen 390R at 2% (or 392R with more colored bands) being mistaken for 3.9K by people in the past.