Wednesday, January 13, 2010

Chapter 2 - Exercise 7 Part 2

Taking apart a relay - fun but a little frustrating. It took about 5 minutes or so to shave away enough plastic for me to remove all four sides. Wear gloves if you can and don't cut yourself... that plastic is tough and I found the best way to remove it was to cut into the sides like your cutting out a half moon scoop... don't try to cut it away in straight slices downward.

After you're done, you'll have a nice little peeled away relay to examine... and it's fairly easy to figure out how it works, too... just like the book describes, you can see the small piece of metal that will move from one post to another. In one of the photos here, you can see the small metal piece in its default location... no voltage applied.

In another photo, I've moved the small metal piece with my finger... a closer look at your relay will show you how the metal posts on the bottom (top?) of the relay connect to the inner workings. Very cool stuff.


  1. This is why engineers made rotary tools such as the Dremel. A simple cutting disk at low speed will quickly open up the relay (remember to wear eye protection).

  2. Its handy to see this up close as the images in the book are quite small. i was quite reluctant to do this to one of my relays as I don't really want to waste one.

    As for using a Dremel I think Jim is trying to stick to the books way of doing things as much as possible. Although using a rotary cutting tool would have been a lot quicker and probably safer.

  3. Trust me - I have a Dremel and I know how to use it! :)

    Andrew is correct, however... I'm trying to follow all the examples in the book - not everyone has a Dremel and I'm glad I was able to provide an estimate on how long this takes...

    Again, use gloves and be VERY CAREFUL with the blade!

  4. I used my Dremel on this, but I don't think it was any faster than what James did with an xacto. You have to go slow so you don't take off too much and mess up the interior. My relay was still functional afterwards so I used it in the experiment just to see it in action. I've got a video of it on my phone I'll try and get it up on youTube and post a link.

    Wishing you all solid connections