Changes

==Introduction==

===Breadboards are the best===

We’ll be using three components (a 9V battery, an LED, and a resistor), plus a very special piece of equipment: the breadboard. The '''breadboard''' is an incredibly handy tool used to rapidly assemble and modify a circuit; to '''prototype''' without the need to solder. A series of isolated metal rails are mounted inside a plastic housing, which can be accessed through holes on the breadboard's front face. The rails themselves allow you to electrically connect components, and the holes in the plastic housing hold the components in place. Take a look at the top face and the internal connections:

'''Setting it up'''

Push those legs in all the way! Now you have access to power from both the top and bottom of the breadboard. You won’t always need to do this; in fact, you may encounter projects which require more than one source of power, in which case you most assuredly will ''not'' want to do this. But since we’ll only be using one source of power in this course (the 9V battery), wiring the same power to both the top and the bottom makes building the circuits easier.

===Connecting the components===

{| class="wikitable"

|1. the positive rail to the long leg of the LED

|}

Your complete circuit should now look something like this:

and your LED should be lit! Here’s another important note: as long as you’re correctly following the internal connections of the breadboard, it’s up to you where on the breadboard you wire up your circuit. It also doesn’t matter which order you place your resistor and LED in: since there is only one path for the current to take, the current is the same everywhere, and it makes no difference which component comes first. So you could also connect your circuit in a different way and it would function exactly the same:

===Voltage Source===

A voltage source creates a potential difference; in the analogy, it is the pump pushing water up to the top floor of the house. There are many types of voltage sources; the most common is the battery. Batteries are represented in schematics as such:

===LEDs===

The '''LED''' is a special type of diode that emits light when current flows through it. “That’s great!”, you’ll say, “But what in the world is a diode?” A '''diode''' is a ''one-way voltage-controlled current gate''. We won’t get into the semiconducting properties of the materials which make up diodes; you can simply think of them as a valve in the water analogy - one that only works if the pump pushes water high enough into the system. The diode '''insulates''' when there isn’t enough voltage across it; no current will flow through. When enough voltage ''is'' dropped across is (called the ''forward voltage''), it opens up and allows current to flow through - it '''conducts'''. In the case of a light emitting diode, when the gate opens and current is flowing, part of the energy of that flowing current is converted into photons; light!

===Resistor===

Resistors are not polarized; you can connect them in either direction, and they will function the same. Their ''nominal resistance'' is stated in Ohms (Ω).

<math>V = IR_{min}</math>

<math>I =3mA</math>

Now turn off your iron, and return all the tools back to their rightful positions in the shop - ''but be mindful of the iron, cradle, and station''. The iron needs to cool down before storing it. Let it sit for five to ten minutes, and then pack it up as well.