Rodney Keeling

Welcome to the first post of a new series of posts — Electronics 101! In these posts, I will go over ideas, concepts, components, project ideas, and examples of everything electronics and electronics hacking! The first post or two should be pretty basic (covering resistors, voltage, the basics) to get a steady ground for whomever may be viewing. Then on to microcontrollers, transistors, different ICs (LM555, LM741, etc), logic devices, and more! To start, I’ll brief over resistors, voltage, current, and LEDs.

If this is your absolute first time learning about electronics, I suggest you go out to buy a book on electronics if you are interested. This first post will be very brief with the basics, so keep in mind my haste.

Electricity:
The most common and helpful analogy to understand current, voltage, and resistance is the water pipe analogy. Take, for example, the idea of electric current. This is analogous to the amount of water going through a pipe — the pipe being a conductor in electrical terminology. The voltage is compared to the amount of pressure across a component. One may have a hose that has low pressure or high pressure. Finally, resistance is analogous to the size of the hose — a greater diameter for the pipe/hose, the less resistance there is. These three concepts are all related with a very simple equation called Ohm’s Law:
V = IR
With V being voltage in Volts; I being current in Amps; and R being resistance in Ohms. For example, if you have a 12V voltage source and a 100Ω resistor (Ω pronounced “ohm”), that would yield:
12 = 100*I
Solving for I, you get the current being equal to 0.12A or 120mA.
Brilliant.
Okay, now on to schematics.

Schematics:
Schematics are a way of representing electrical components on paper or in digital form. Here is a very simple schematic containing three components:

As you can see, that component on the left has a voltage assigned to it (6V). This is the schematic symbol for a battery. More commonly, you will see a circle with a + and – sign in it — this is a voltage source. Next, the jagged, squiggly line represents a resistor, and the last component, the one labeled LED, represents and LED. However, this symbol is a bit deceiving because it does not have the arrows that normally come out of the triangle drawn in; this is actually the schematic symbol for a normal diode. This circuit would light up the LED and make everyone watching happy. Wee. Also, that symbol on the very bottom right represents common ground, which just means 0V.

LEDs:
LED stands for Light Emitting Diode. You may wonder what a diode is, but that’s too bad for you. I shall go over that within the next few posts. An LED is mostly used as a sign for the user of whatever you are making (e.g. it may represent ON/OFF for some system), and they are really simple to work with. Just make sure you connect them the correct way and you always use a resistor in series with them. To determine which way to connect it, simply look at its legs! This is also a great way to get slapped when flirting with the ladies. Anyway, as you can see in the lovely image below (courtesy of Society of Robots), there are two legs to an LED, the cathode and the anode. The cathode is the negative side (or the side with the shorter leg), and the anode is the positive side (the leg with the longer leg).

Well, that’s about it for the very basics. Next time will be more interesting, I promise. I plan to cover transistors, capacitors, diodes, and voltage regulators next time, and perhaps even a simple project. :]
Until next time, friends!

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