LED Voltage

[Mr.Chips]

I'm using an old PC case as my control box and it has a few LED's on the front. Thought I might connect them to the various power sources so I could see if one wasn't on, or working.

My question is what is the typical voltage to little LED's like these?

I have 5V DC and 28V DC I would like to monitor. If this is too high of a voltage to apply to the LED's what size resistor would I need to drop the voltage down?

Thanks

[Al_The_Man]

LED's are current operated devices, (forward biased diodes) you need a series resistor.
A rough guide if you don't know the specs. is 330ohm for 5vdc and 1200 ohm for 24vdc.

[Mr.Chips]

Originally Posted by Al_The_Man LED's are current operated devices, (forward biased diodes) you need a series resistor. A rough guide if you don't know the specs. is 330ohm for 5vdc and 1200 ohm for 24vdc.

Thanks AL,

I pick some up and give it a try.

[Al_The_Man]

BTW if you get the polarity wrong, it won't screw anything up, just that the LED won't light.
Al.