Electronics makes me feel stupid
July 3, 2011 3:04 PM   Subscribe

Being an electronics wizard, what do you wish you'd known when you started out?

I'm trying to teach myself electronics but, not being the logical sort, I find it extremely difficult to get my head around anything but the basics. It's an overwhelming subject.

Nevertheless, I will persevere some more.

When you were starting out, what do you wish you had known?

Do you use any tricks or such that you wish you'd known earlier on? Do you know something now that would have made the learning process so much easier for you?
posted by run"monty to Technology (9 answers total) 23 users marked this as a favorite

The more detailed hydraulic analogies are helpful.

Art of Electronics is an excellent book once you want more than a very basic understanding.
posted by trevyn at 3:23 PM on July 3, 2011

Best answer: Here's an answer I gave to a similar question.
posted by krilli at 4:08 PM on July 3, 2011

It's hard to give specifics without knowing the kinds of things that are tripping you up. But generically:
  • There's no such thing as absolute voltage. Voltage is always a relative measurement: "this point is X volts higher than this point". If the second point is not specified, then it's implicitly in reference to ground. An analogy would be elevation -- when you give the elevation of some location, unless otherwise specified, it's relative to sea level. When you talk about the voltage across something, then it's specifically giving you the two points as the two terminals of the device.
  • Speaking of the word ground, that is perhaps the most confusing word in all of electronics because it has several different meanings. In most contexts it just means "the reference point to which we will refer to all voltages". The choice of this reference is completely arbitrary, but it's usually some convenient place like the lower side of the supply. Or, if the circuit deals with things that oscillate then you usually split the supply in two and call the middle ground, so that you have e.g. +10, GND, -10. But this is exactly equivalent to a single +20 supply with a signal biased to sit at +10. In other words, the choice of which point to call ground doesn't affect the actual circuit in any way.
  • Circuit schematics are not arbitrary, they are drawn in a specific way meant to aid understanding. Normally vertical position on the page corresponds to voltage, which means you have your positive supply at the top and your ground at the bottom. Circuit elements that are drawn vertically usually have a higher voltage at the top node than at the bottom. This is not an absolute, as you can draw a circuit any way you like, but there tends to be a language to how they are drawn which is meant to visually show you how the circuit works.
  • Don't get hung up on trying to think about the flow electrons. The mental model of current should be one of a generic fluid flow. This fluid naturally wants to flow from high to low elevation, so that's what it does across dissipative elements like resistors. It takes a "pump" to push it up hill from lower elevation to higher elevation, so to do that requires some kind of external oomph (usually the battery or power supply), but in certain cases this can be stored energy that is released (such as a capacitor.) In actuality this is all reversed, but that's not really relevant.
If you give specifics of the kind of things that are giving you trouble then I'm sure we could give more specific advise.
posted by Rhomboid at 5:19 PM on July 3, 2011 [1 favorite]

I don't know much, but here are a few concepts that make me feel that I know more than some:


equivalent circuits - every circuit, no matter how complicated, behaves like a voltage in series with a resistance.

Combining dividers, equivalent circuits, and the water analogy, and I finally got what 'matching impedances' means.

In analog land, a circuit has one behavior with a fixed DC load, and a different one for a varying AC signal. Sometimes you care about the AC, sometimes you care about the DC.

Setting amplifier gain with controlled negative feedback is a thing of beauty.

Good Luck!

(By the way, for me the theory comes more easily, but I find myself looking at a diagram or the internals of something and thinking "What the hell are all those things?". I found a book, Practical Electronics for Inventors, by Scherz, filled with pictures so I can say, "Oh, yeah, those round deallies are probably capacitors". In addition, it has an appendix "Power Distribution and Home Wiring". It started at the spinning rotors under a waterfall, and went right up to the house sockets, two-prong, grounded, and three phase heavy equipment. Very cool.)
posted by benito.strauss at 5:42 PM on July 3, 2011 [1 favorite]

I'm not a wizard by any stretch but the thing that I started seeing after a while is that certain portions of circuits are like blocks of code in a computer program. Recently, I was watching a guy fix a quantitative PCR instrument a while back and I could have taken a marker and drawn lines on the board where this section drove the stepper motors, this part was a power supply for the peltier junction, this part...etc. I'm not quite to where I'm ready to build my own quarter of a million dollar scientific instruments, but once you can break it down into understandable subassemblies it's no longer magic.

The Art of Electronics and Practical Electronics for Inventors are both really good. The Make: Electronics book is a reasonably good lab manual if you're wanting to to a hands on section.
posted by Kid Charlemagne at 6:27 PM on July 3, 2011

Best answer: I started studying electronics when vacuum tubes were still king, Nuvistors were the coming thing, and transistors unreliable, expensive experimental devices that would never work well in the then-current high voltage equipment designs based on vacuum tubes. There were no Integrated Circuits of any kind (analog or digital), zener diodes, or operational amplifiers, and the only "solid state" rectifiers were big stacks of selenium and copper oxide rectifiers that cost a lot, and looked funny in many applications.

I've been shocked, amazed, inspired, and gob smacked in every year since 1963 by the advances in electronic theory, in devices, and in supporting technology. When I saw the first working all-transistor radio that crossed my path, in its little leather case, pouring out Elvis Presley and The Lettermen from a 9v battery, I damned near cried in wonder. I still have the Bowmar Brain 901D I bought, second-hand, for $100, knowing full well that it would display erroneous output if ever asked to divide by zero.

"Being an electronics wizard, what do you wish you'd known when you started out?"

I wish I'd known something, anything, about solid state physics, when I started; I wouldn't have felt like I'm constantly playing catch up with the solid state revolution, ever since. I wish I'd had a better foundation in math, beyond just calculus and simple statistics when I started studying electronics, as it would have made understanding a lot of the IEEE papers and other engineering data I've read a lot easier to understand; as it is, I've painfully gone back to school, a couple of times, when the math I knew was no longer sufficient for the understanding I wanted in the study of electronics. I wish I'd known a lot more about applied and theoretical physics, like heat flow, photoelectric effect, ionizing radiation, quanta and quantum mechanics, etc.; if I'd just had a better sense of the convertibility of particle and wave phenomenon in physics frames of reference, I'd have been years and money ahead of myself, when I hit these topics, head on, and stupidly uninformed.

And really, I would have been much better off with a much more extensive understanding of the history of science, than ever I have possessed. I learned Ohm's Law, and used it daily, for a full decade before I even knew that Ohm's first name was Georg. I'm sorry about that; if you stand on the shoulders of giants, simple decency demands that you can name the giants, and perhaps, find their headstones in a wider world.
posted by paulsc at 6:29 PM on July 3, 2011 [7 favorites]

Learn how to bias a common-emitter single-BJT-transistor stage; knowing this actually got me my first job out of college.

Learn how to design an ideal op-amp inverting and non-inverting stage.

Learn simple one-pole RC low- and high-pass filters.

These three things will get you a long, long way!
posted by ZenMasterThis at 7:12 PM on July 3, 2011

From a practical standpoint (as opposed to circuit theory): it's definitely worth spending the money on a decent soldering iron. Interconnects (wiring and connectors) are far more important than a textbook will tell you (except maybe a design-for-manufacture textbook).

I wish I'd known something, anything, about solid state physics, when I started

I grew up in the transistor (and IC) age but I didn't really grasp how to use transistors in even simple circuits until I learned the physics behind them. That could just be me though.
posted by hattifattener at 7:25 PM on July 3, 2011

When a bipolar junction transistor is in its ON state, to a crude approximation all three terminals are connected together.

Similarly, when it's OFF, to a crude approximation all three terminals are disconnected from each other.

A bipolar transistor is a current amplifier: the more current flows into its base, the more current flows through its emitter and collector.

Learn to read a schematic diagram. A good schematic, organized to convey the structure and function of its circuits, can help you understand how the circuits function.
posted by exphysicist345 at 12:30 AM on July 4, 2011

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