How to get started with electronics?

My experience with electronics so far has been from just building kits, which I guess is the electronics equivalent of assembling flat-pack furniture: Someone has already done all the design work and all you have to do is follow the instructions to put the pieces together. I’ve learned some skills along the way, like soldering, desoldering, reading resistor values, and roughly what capacitors, optocouplers, shift registers etc work.

I got an Arduino for xmas, and I’d like to start playing about with it, but my first attempts have mostly shown that I don’t know enough about electrical engineering to get started with much confidence. I’ve seen that there are forums on the Arduino site, and I might go and post there, but a lot of the questions seem to be quite Arduino-specific and seem to assume a basic level of knowledge on the electronics side that I don’t have. So, seeing as it’s so nice and friendly here, I thought I’d ask you guys where and how a complete novice could get some basic information.

To give an example of the kind of level of knowledge I’m at, one of the first tutorials for beginners they have is an LED that’s controlled by a switch. So far so easy, except that a circuit like that involves a couple of resistors. Now my head is filled with questions like these:

  • One book I have says early on: “LEDs have the interesting property that no matter how much current flows through them, there will always be about 2V between their pins”. Why? And how would I have found that out otherwise? Is it 2V for all different types of resistors? What about different sorts of components, is there a voltage difference in those? If there is, how do I find out the voltage differences?

  • The book goes on to say that the current flowing through the circuit should be around 10mA (and also says that LEDs would be happy with anything between 5 and 30mA), and demonstrates how Ohm’s Law shows that the ideal resistor for that would be 300 ohms, so they pick a 270 because it’s the closest thing that’s manufactured. Is the 10mA thing true of all circuits, or is that something specific to LEDs? If the ideal number of amps varies, how do I calculate that or look it up?

  • The books I’ve been using to learn from use an analogy involving water pumps (representing power supplies), water wheels (components like LEDs), and narrower stretches of pipe (resistors). I’m aware that the analogy is imperfect, but it makes no attempt to explain why the resistor needs to go AFTER an LED in a circuit. Shouldn’t it be before the circuit, to step down the amps before the current reaches the LED?

I’m not looking for answers to those questions here (although feel free to enlighten me!), more just a way for someone like me to learn more about this stuff myself. I’m a pretty competent programmer, and I’m not completely awful with a soldering so I imagine I could do some quite cool stuff with Arduino (maybe even some new things to work with a Shruthi!) but not knowing enough about electronics to know how to build circuits from them is a bit of a problem…

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say you have two components in series. like 2 resistors. then it is obvious that the current that goes through one of them also has to go through the other in order to go from one potential to the other. the current that can go through a resistor is determined by the voltage and the resistance. that’s ohm’s law:
U=R*I
if you have just one led between + and - the led will draw more and more current, just because it can. that results in more light, until it overheats and is destroyed. so you’ll need a resistance in series (no matter where, before or after) in order to limit the current that may go through itself AND the led, as they’re in series. there’s no other way to go, so the same current must go through all parts of this line. the voltage drops add up in that one line but the currents stay the same (which means the resistor eats one part of the voltage, the led eats the other part, and it must be that way because on one side you have say 5V and on the other 0V, so it has to be consumed somewhere on the way).

it’s exactly the other way with components in parallel. there the currents add (because 2 can flow at the same time, obviously) but the voltage is the same for both ways in parallel. you can really compare that to 2 streams of water.

but there are a lot of books about electricity available on ebay or amazon, or even at the next thrift store or library. maybe a school book. i’ve found them at all of these places, also on the internet you can find tutorials and explanations of about everything.

oh yes, there actually ARE good books for beginners and even related to musical instruments!
like
Craig Anderton’s “Do-it-yourself Projects for Guitarists” for example, this has some good explanations for beginners.
or Reed Ghazala’s Circuit Bending.
also Nicolas Collins’s Handmade electronic music.

these are actually great books that are not written for little kids.

If you are cheap like me this is not too bad of a site http://www.allaboutcircuits.com/

V = IR is your friend. play around with some free circuit simulators if you dont have the confidence to play with the real thing.

Get some books, and get yourself a nice breadboard, buy a cheap parts and experiment. If you stick with low voltages like 5vdc there is much you can do to blow something up. I learned a lot from trial and error, building from schematics on a breadboard and then just modifying those circuits, having a breadboard makes that SO much easier!

You said you got an arduino, well try building one on a breadboard and every step learn what each component does to contribute to the circuit. There are good books and there is a wealth on the internet also. Also learn to read a schematic, learning that will help you visualize the flow of electricity and also what and why components do what they do.

Great advice, guys!

@Rosch: I’m still not sure about the relationship between Volts and Amps (I know the equation, but I’m having trouble visualising what it means), but basically if voltage and current come from a source and go to ground, there need to be components in between to reduce both of those (to prevent a short), but the order doesn’t matter in a serial circuit. Is that about right?

Also, I’ll take a look at the book links, see which one looks like it would suit me best. I don’t think I’ll limit myself exclusively to music projects, but I guess the workings of a guitar pedal or synth or circuit-bent audio toy at least relates to something I already know something about, so it might make it easier.

@ Frapacrinko and EATYone: Cheers. Online resources are always good, particularly interactive ones that let me play with stuff virtually before breaking components in the real world (I know the components are all cheap, but it’s not easy for me to get replacements where I live, so I’m trying to make the best use of what I have)

@Starfire: Got a couple of Arduino books (Getting Started With Arduino and 30 Arduino Projects for the Evil Genius), as well as a “starter kit” with a breadboard and a bunch of common components. It’s cool to be playing with electronics without having to break out the soldering iron, at least to start with. I think I’ll be able to get pretty comfortable with reading circuit diagrams as well, once I have a better idea about exactly what happens between 5V and 0V.

the voltage is basically a tension. if you have a wire with 0V on both sides, or 5V on both sides, there will not be a current going from one side to another. a current appears as soon as there’s a tension between 2 points and a way that the energy can take between these points in order to equalise both sides again. the resistance determines how long it takes to achieve that (how much current can flow at a time).
there may be requirements in special situations in which order components have to be placed. but in the situation here, to limit the current flow to protect an led it has the same effect if the resistor or led comes first, because the led will take all it can get and the resistor always consumes the same amount of energy (heat dissipation) at a time and a given voltage. the result is that the led will just have the energy that is allowed by R.

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