1. Home
  2. Hobby Electronics Basics
  3. 12 Vdc led running hot

12 Vdc led running hot

I bought some 12 VDC 5 mm red leds.

They work find but...

when I touch the wires going into the led, they were hot enough that I had to remove my hand.

That does not seem normal.

Thanks.

Reply to
AK
Loading thread data ...

Don*t touch them, that would be normal.

Who in the world touches LED wires?

w-

Reply to
Helmut Wabnig

At what current are you running them?

Reply to
Tom Biasi

Right. More specifically - how are you running them? I.e., what are you using to supply the 12v? E.g., a plain old 12v battery will cause way too much current (& heat). LED supplies need to be current limited.

Reply to
Bob Engelhardt

Sounds broken, got a picture/ link of what you bought?

GH

Reply to
George Herold

Maybe you could supply some info like the datasheet on the leds?

Too hot to touch is usually too hot.

Reply to
default

** The heat is from a resistor in series with the 5mm LED.

Red LEDs only take 1.7 volts so the rest is dropped by a resistor.

..... Phil

Reply to
Phil Allison

I found out that the led is actually 9 volt.

It was labeled at 12 volts which was way too much.

After switching to 9 volts, it runs much cooler.

Andy

P.S. I wonder if the Chinese fighter jets have similar mistakes. :-)

Reply to
AK

A lot of times the asian folks selling stuff are nontechnical, best to take any descriptions with a grain of salt and form your own opinion as to suitability and accuracy.

Reply to
Rheilly Phoull

They're 'current-orientated devices' for want of a better term for it. To make things a bit easier, manufacturers will quote the Vf for each LED which is the recommended level of forward bias voltage required to provide the optimum amount of current vs. longevity allowing for such a device's dynamic resistance as its barrier height potential is overcome. I could have probably written that better, but not on a Sunday afternoon after a decent bottle of Claret. :)

--
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
protocols, whether for profit or not, is conditional upon a charge of  
GBP10.00 per reproduction. Publication in this manner via non-Usenet  
protocols constitutes acceptance of this condition.
Reply to
Cursitor Doom

Thanks Mr. Doom

Andy

Reply to
AK

It's a easy way to make a test in LED during the commissioning.

Reply to
Tobias Gadelha

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.