Will LEDs get burned out by too much current?

[greenhawk]

Hi all, this is my first (of many, hopefully!) post here. I am just starting out with electronics and have a semi-novice knowledge of electronics.

I have a quick problem I could use some help with tonight.

I have 36 LEDs hooked up to an old AD/DC wallwort, and I notice it seems dim with a flicker. I *THINK* each LED is capable of around 20ma, and there's 36 of them.

Just a thought, but that would mean my absolute max current would be 720ma, a far cry from the 1/3 of that (200ma) it's using now -- which means if the LEDs are only getting 1/3 the current they want, that could cause a flicker.

My idea would be to put, say, 600ma through it and see what happens. I wonder if it will still have the slight flicker. Or, conversely, what if I put on 1000ma and gave it a resistor that downscales it to around that 600-something mark? Maybe that would better eliminate the flicker, because then it's not just freely letting all the current through... Because I haven't eliminated the wall wort as the cause of the flicker...

I should also note the wallwort is 12VDC, 200ma. I also have a 12VDC, 1000ma unit on deck that I hope to be able to put to good use.

Any ideas?

 

[(*steve*)]

Yes, too much current will kill LEDs

How are the LEDs connected? Series, or parallel?

If they are connected up in series then the TOTAL current should be about 20mA.

If they are connected in parallel (a bad thing generally) then the current will be n * 20 mA max.

The flickering is most likely due to the power supply not being filtered and you are seeing flickering at mains frequency. I have a set of Christmas lights that have that sort of annoying flicker which is most noticeable when you're not looking directly at them.

LEDs should always have a series resistor or some other device to limit current. To do otherwise is to play Russian roulette (sometimes with all chambers loaded)

Take a look here. We get asked this stuff all the time.