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.


  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.

  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!


  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.