One of the best ways to learn about LEDs is by tinkering with them. While encased in lamps, LEDs might be tiny, sensitive, and hard to understand, but when out in the wild they are affordable, easy to use, and rather simple devices. This makes them ideal for experimentation and a great way to learn the basics of electronics.
The previous mention of do-it-yourself LEDs covered the Throwie, the simplest of the LED circuits. It combines a battery and an LED into a easy to understand device that anyone can make in minutes. The next step up from that two-part project is adding a resistor to the mix. This will allow you to adjust your circuit so that the proper amount of power is going to the LEDs which will, in turn, ensure they get the maximum lifetime possible as well as the optimum brightness. Without a resistor, its easy to send too much power to the LEDs and shorten their lives significantly, or simply break them.
To figure out the resistor you need in your LED circuit, some basic math will be required. The formula is based on Ohms law, where V = voltage across the resistor, I = the current through the resistor, and R is the resistor value. Here are three ways of stating Ohms law:
If you were anxiously waiting to get to this page and see a list of
thousands of iPod games, I'm sorry to disappoint you. Most iPod models
can't hope to replace the gaming experience that you can have on Macs,
PCs, PDAs, smartphones, Game Boys, or PlayStations, but if you play games
occasionally and you don't want to buy one of these other devices, most
iPods can keep you entertained, particularly the 5G and 6G iPods, and the
3G nano, which can play games for sale in the iTunes Store.
Oddly, the iPod touch has no built-in games, and can't use the ones
available at the iTunes Store, either.
Most iPods (2G5G iPods, 1 and 2G nanos, and all minis) have four
built-in games. You can find the games by bringing up the main menu, and
choosing Extras > Games:
Brick: In this "Breakout" style
game, you knock out bricks with a bouncing ball to gain points. The
Click Wheel is a perfect interface for this game, as you move your
finger clockwise or counterclockwise to move the paddle left or
One day a colleague and I were walking along the crowded waterfront in San Francisco. Coming toward us was a trio of young African-American men who were joking and playing. When we passed, I greeted them. Just as the last person walked by I heard him say, “Thanks for seeing us.”
It took a minute for that to register. My companion said, “Did you hear what I heard?” It took me a moment before I could respond with, “Yes.” My heart was breaking.
How could it be that I would be thanked for merely seeing someone? It took all of my self-control not to run back to those young men, gather them in my arms, and apologize for every person who had ever overlooked them, averted their eyes, or turned away. What must it be like to move through a world that refuses to meet one’s eyes, that refuses to acknowledge one’s very existence?
I could make an analysis and write this piece solely about the kind of pervasive racism which creates a very specific and limiting box in which African-American men are expected to live (and why they might feel invisible). Yet as I scan the world with those young men still in my heart, I notice that many kinds of people are often overlooked. The bag clerk at the grocery market, the person at the front desk, the folks who carry our mail or clean our streets or who are considered too old, or too young, or too…