Thursday, February 11, 2010

Make Electronics (8) Relays

All but one of my orders came in over the past few days and I decided to tackle the next few experiments in Make: Electronics. I worked my way through  switches. No problem other than hooking everything up with alligator clips.

The author, Charles Platt, has you tear apart one of the relays to see how they work, as shown to the left.

Essentially a relay is a switch that turns on another switch. It has a small electro-magnet that closes another circuit when it gets a little juice. After I played around with this for a bit, I remembered making one of these using a nail with wire wrapped around it for the electro-magnet part when I was in 5th or 6th grade. When you turned the magnet on, it attracted another bit of metal that then closed a switch which turned on a light bulb. Almost the same experiment as shown in the Make: Electronics, only using nails, wire and a block of wood to hold it all together. How many classrooms today allow elementary kids hunks of wood, nails, hammers, real cutting utensils (not safety scissors) and dry cell batteries?

As you can see here, I have the first part of Experiment 7 using the relay switch put together using alligator clips. It works, but shake the table and it all falls apart. Thankfully, the next step is to start using a breadboard to build circuits.

Here is the completed circuit built on a breadboard. Push the red button and one LED goes off and the other turns on.

Unfortunately, the next experiment called for a capacitor and it's in the one order that hasn't arrived as of yet.

So I spent another thirty minutes just messing around building different circuits on the breadboard. I bought a box of pre-cut wires on the advice of the author and that makes throwing things together much easier. You could cut a bunch of wires to different lengths, but for around $5 someone else did that for me.  Lazy....yes.  Useful....oh yes!

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[Images all taken by Al Gunn]

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