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 Post subject: Electronics FAQ
PostPosted: Tue Jun 07, 2011 6:34 pm 
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Joined: Mon Sep 13, 2010 12:18 am
Posts: 116
Location: Southern United States
I'm new to electronics; how do I get started?

You will need a couple of things: a basic background in mathematics and a "lab" of some kind. You'll need to do basic algebra for simple electronics; later on, you will want to learn trigonometry, discrete math, and possibly even some basic calculus and linear algebra. These you can learn these things progressive; however, you cannot do electronics effectively without a basic understanding of algebra. (you'll see why later in this post)

It goes without saying that you will probably want the opportunity to practice what you've learned, and you are probably eager to build new circuits if you are reading this. Setting up a small area to work in will give you this opportunity. It can be as simple as corner of your room, (you'll probably want at least 5'x1' to work in) a bench in your garage, or a purposefully built electronics lab at your school. If you are setting up your own lab, there are several ways you can acquire materials for it. You can buy the starting materials in a kit, or you can put one together. You will probably want the following:

  • A breadboard for prototyping (anywhere from $10-$30 depending on size)
  • A couple of spools of insulated 22AWG wire ($5-$10 for 100')
    • one of which is stranded
    • one of which is solid
  • A power supply of some kind
    • Rechargable batteries (9V or AA will probably do)
    • A lab power supply - much more expensive than batteries, but easier to use.
  • Some discrete components:
    • A diverse collection of resistors of varying resistance; extremely cheap in bulk (this appears to be a good kit at $14.99)
    • Various ceramic capacitors of varying capacitance; cheap in bulk. (this appears to be a good kit at $26.95
    • Some LEDs; these aren't as cheap, but you won't need a lot of diversity in these. (this might be an OK deal at $7.95)
  • A digital multimeter; an OK one can be had for about $15 or so

All in all, you will probably spend somewhere between $75-$100 USD getting yourself set up. Sometimes, you can find electronics trainers which are significantly cheaper, but offer a little less variety. You'll know of these because they have spring contacts. These are often a good start, as well, but seem to be harder to find these days. If it seems like a large investment, you'd be right: unfortunately, until we invent something like the replicator technology in Star Trek, this is probably going to be a fact of getting started. Fortunately, with the breadboard, you can reuse most of these components.

You'll probably also want some way to learn. If you're in college, your best bet is to take some electronics courses as an elective; not only will you learn electronics from this, but you'll also have something to put on your resume. If this is not feasible, then there are various websites and textbooks devoted to this topic. (todo: find some examples of this)

What are some basic things I need to know about electricity?

The most important thing you need to know about electricity is that it is the flow of electrons. You can think of an electrical circuit kind of like a flowing river: electrons will flow from their source (traditionally, the positive terminal of a power supply) to an endpoint. (traditionally, the negative terminal) Note, that unlike a river, the source and the destination are related to each other.

With regards to electricity, we look at it in three ways. We can talk about the number of electrons in the circuit, or its charge. (represented by Q) This is rarely useful at a high level, however. We can also talk about the flow of electrons through a circuit at any given time: this is current, and is usually represented by I. Finally, we can talk about the potential energy in the electrons, which is called voltage. (V)

Now, we can arrange a circuit in two ways: we can talk about series circuits, and parallel circuits. In a series circuit, there is only one path the electrons can take, while in a parallel circuit, the circuit forks into two or more series circuits. In a series circuit, current is constant across the entire circuit, while voltage drops over time. If you add up the sum of the voltage drops, however, you find that it is the same as the original voltage.

What do you mean by "traditionally" in the above FAQ?

That is to say, that's not really how it works. The above model of electron flow is called "conventional flow", and was developed when our understanding of electronics was in its infancy. Democritus is often credited with formulating atomic theory; however, it wasn't really until the beginning of the 1800s before atomic theory was taken seriously, and it wasn't until much later that we got a clearer picture of the atom. We knew something was flowing in early electrical experiments, we just didn't know in what direction. We thought the flow went from positive to negative; we turned out to be wrong.

The correct flow model is called "electron flow", which models electrons flowing from the negative terminal of a power source to its positive terminal. In reality, as long as you're consistent in which model you use, either model works fine.

(todo: write more)

What is resistance?

Conductance is the degree to which a circuit element facilitates electrical current. If this is the case, then resistance is the inverse value: the degree to which electrical current is inhibited by a circuit element. Objects with nonzero resistance are called resistors, and resistance is measured in Ohms. Resistors have the effect of causing voltage to drop when current passes through them. Using our river analogy, you can think of it this way: an ideal river will allow water to flow through it without any trouble. However, let's say we construct a dam in the river. A perfect dam has infinite resistance because it completely inhibits the flow of the river. If we were to build an aperture in the dam, then some water could get through, but significantly less water will do so.

In reality, very few things in the real world have zero resistance. For instance, we tend to think of wires as being perfect conductors. (i.e., having zero resistance) However, this usually isn't the case; wires generally have a resistance dependent on their length. You can calculate the resistance of such a wire if you know what material it is made of, (or resistivity, r) it's length,(l) and its cross-sectional area.(a) If you know these values, then its resistance is calculated as R = (r * l)/a. There are materials that, under very strict conditions, have zero resistivity, and these are called superconductors. However, superconductors are not everyday things, and while the holy grail for a room-temperature superconductor is ongoing, it's not apparent that we will ever find one.

(todo, write more)

"Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. -- C. Babbage

 Post subject: Re: Electronics FAQ
PostPosted: Mon Sep 19, 2011 3:53 pm 

Joined: Sun Mar 20, 2011 8:19 pm
Posts: 26
You left out a switch :D

PostPosted: Wed Jan 03, 2018 2:53 am 

Joined: Wed Jan 03, 2018 2:24 am
Posts: 53

 Post subject: Re: Electronics FAQ
PostPosted: Tue Apr 30, 2019 6:19 pm 

Joined: Wed Mar 13, 2019 4:37 am
Posts: 28345

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