So now we're going to get to play around with resistors and LEDs for a bit.
This exercise was a good one for me because I learned to trust my multimeter, not my eyes. I'll explain shortly.
You'll be using a variety of components - LEDs, resistors, gator clips, batteries, battery holder, and your multimeter. There's a great tutorial (page 15) on how to read the stripes on resistors - don't skip it. It's titled decoding, and that's exactly you'll be doing - trying to figure out these tiny little colors and convert them to a number.
If you're like me and purchased the fancy blue ones, you'll likely discover just how difficult it is to distinguish some of these colors! Brown and black (on some) look identical... others are hard to tell the difference between orange and red. Later in the book I see the author is going to have you using a helping hand (or 3rd hand) device that usually comes with a magnifying glass; I already have one so it was a huge help. If you've got one (or a simple magnifying glass) keep it in your toolkit - it'll come in handy.
First off, I made a HUGE error when tracking down the 470 ohm resistor; I purchased a big bundle/mix of resistors and thought I had the decoding done properly. Wrong. My trusty multimeter showed me that I didn't have the right resistor... and this little setback also made me realize how fast and easy it is to determine a resistor's value with a multimeter.
That's not to say you shouldn't try and convert using the color/number system... do that first and then use your multimeter to double-check yourself. On a positive note, I was able to find the 1k and 2.2k resistors using just the color codes. I feel good about myself.
So, up next is the experiment that demonstrates how voltage and resistance are inversely proportional... more resistance, less voltage. You really can tell the difference between the 470 ohm, 1k, and 2.2k resistors after you light up that LED... it gets brighter as the resistance drops. (Hard to tell from the pictures, but the LED does change in intensity.)
This was a fun exercise... the gator clips are a little frustrating at times trying to hold those small wires. And, as I mentioned, these dark blue resistors I purchased aren't the easiest to decypher. Keep that in mind as you buy resistors - I think I'll stick with the light tan colored ones in the future.
Okay, that about does it for Exercise 3... here's what you should have taken from your reading and the exercise:
* You can build a simple flashlight (but weak) using a few batteries, a resistor and a single LED.
* Multimeters are good for verifying a resistor's value
* You can blame Andre Marie Ampere if you don't like the Flourine in your water supply
* Resistors are small; when they fall on the floor, you'll never find them again
* There is a method to the color madness of resistors
* Four color stripes are more confusing than three
* It's okay to connect the long LED wire to the negative terminal - it won't hurt but it also won't light up
* A small resistor (in size) doesn't mean a smaller value... that surprised me
Tomorrow, I'll finish up Chapter 1 and cover Exercises 4 and 5.