I know I installed them pos/neg correctly (tested with multimeter power and it lights up correctly), however when I make contact properly I only get a quick flicker of light.
I emailed sparkfun customer support and they just said they are generic LED’s from “some factory”.
My current thinking is that either a) There is a short somewhere or b) that I need to use a different resistor (car produces 12V and a LED calculator says I should use something around 330Ohms for a 2V LED, which is a common red LED voltage. The multimeter produces ? voltage and the LEDs come one when I power through that.).
After reading through the multimeter documentation it seems that this particular multimeter has a diode test which when selected gives you the forward voltage of a diode. I guess I will use that to make the proper calculations.
That was my guess to. It’s probably around 2 V. Would having a bigger resistor on there then there should be make them flicker on for a second and then not stay lit?
I’m guessing it might… I guess a smaller resistor would let more power (watts through). Maybe there isn’t enough??
Here is another way of looking at things…
The switch had green LEDs on it to begin with and has a 680 ohm resistor on it. Working an LED calculator backwards using 12V and a 2.5V forward voltage (a guess based on typical green LEDs) I get 15mA.
The LEDs I purchased are cheap basic ones (as in, non-high power/brightness) so they are probably rated at around 15-20mA.
