CHAPTER 11 ■ POWER ON!Building the Power Indicator Circuit
You’re now going to build the power indicator circuit by connecting the parts together with alligator clips
(see Figure 11-2).
- Connect one red alligator clip to the positive terminal of the 9 V battery.
- Connect the other red alligator clip (the other end of the same red jumper)
to one lead (wire) of the resistor. It doesn’t matter which end of the resistor is
connected. - Connect one green alligator clip to the other end of the resistor.
- Connect the other green alligator clip to the anode lead of the red LED. See the
earlier chapter if you don’t remember how to locate the anode lead. - Connect one black alligator clip to the cathode lead of the red LED.
STOP! The last connection is going to be to the other end of the battery. But, you should always check
your circuit before making the final connection to the battery. With only one connection to the battery so far,
no electricity is flowing.
For a moment, pretend you’re a lazy drop of electricity. The battery is a pump shoving you (electricity)
out of the battery and into the wire pipe. You don’t like being outside of the battery. Your mission: Get
back to the battery as quickly and easily (you’re lazy) as possible. If you can find any shortcuts, take them.
Jumping through the air is not easy, so that’s not a shortcut.
Are any metal pieces touching any other metal pieces by accident? Those are great shortcuts.
Make sure that the electricity has no choice but to go out the battery, through the red jumper, through
the resistor, through the green jumper, through the LED, and then into the other end of the battery. This is
the path you want the electricity to take in its quest to return to the battery.
Ready?
- Connect the remaining black clip to the negative terminal of the 9 V battery.
Figure 11-2. Photograph of the assembled power indicator circuit