Friday, January 29, 2010

Chapter 3 - Exercise 13



For this experiment, I used a green LED and a yellow LED. The green one got the 15W treatment followed by 30W. The yellow got 30W but I added in the small copper alligator clip.

As the chapter states, the 15W was a piece of cake - the green LED was still lit well after 2 minutes of holding the iron to it. I even moved the iron's tip very close to the plastic of the LED but it had no negative effect.

Then I switched over the pencil iron to 30W... and held the tip to the wire. After 40 seconds I was a little worried that maybe I'd selected the Super-LED... or that my pencil iron was defective. But near 1m 30sec, the green LED gave its last performance.

So, I threw away the green LED and replaced it with the yellow... plus I added the little copper clip as seen in one of the photos. I held the 30W iron to it for over 2 minutes, but it just kept on shining.

It's always fun to smoke electronic components - we were promised that in the book's sales sheet, right? The green LED sacrificed itself and I will never forget the lesson it taught me - too much heat can be a bad thing. Use the copper clips whenever possible.

RIP Green LED. You will not be forgotten.

3 comments:

  1. The LEDs that seem most vulnerable to heat just happen to be the ones that I tried first: Large, high output, 1cm diamater, bright-white. Subsequently I found that some regular-sized (5mm) LEDs are quite robust, much like the green LED that you describe.

    If I had had more time, I would have done the same experiment with a transistor that was set up to amplify sound. Apply the soldering iron to one leg of the transistor and wait for the noise to stop.

    When I was a teenager I was so intimidated by the warnings about applying excess heat to semiconductors, I was literally afraid to use them.

    ReplyDelete
  2. There you go, folks - a dare from the author himself - try the same experiment with a transistor and email me your results and I'll share a few - a video would be even better!

    Jim

    ReplyDelete
  3. I was amazed how much the "heat sink" effect of the copper alligator clip prolonged the life of the LED. I was using a 40W soldering iron and got 2 minutes of life out of the LED at first. When I added the copper alligator clip the LED lasted for 8 minutes. Yep, I'm an Engineer and I just had to see how long it would last.

    ReplyDelete