# Computing stuff tied to the physical world

## Flashback – Easy Electrons

In Hardware on Oct 3, 2013 at 00:01

The Easy Electrons series is a set of weblog posts which were published end of 2010 and beginning 2011 to try and bring across a bit of intuition w.r.t. electronics.

Many many times, people not trained in electronics struggle with the concepts of voltage vs. current, wonder why some component suddenly overheats, what a capacitor does, why you need a resistor in a certain circuit, or how large that resistor should be.

Unlike software, hardware and electronics are bound by the laws of physics. Painfully so, in fact – you can damage stuff when hooking things up incorrectly, and you can even get hurt if the voltages or currents involved are high enough. And it’s not just AC mains that can hurt you: even a car battery can be dangerous if you don’t know what you’re doing.

Knowing why things happen is extremely important in electronics. And learning the basics is really just a matter of reading up on it and investing a bit of effort. There’s no magic – in fact, there is so much knowledge about electronics nowadays, that you really can predict and explain stuff, even before hooking things up.

Since I loved tinkering with electronics as a teenager, I was lucky to gain a good deal of very intuitive knowledge about electronics early on. So much so, that basic DC electricity knowledge became second nature to me. Ohm’s law is not some technical rule, it’s obvious – the linear relation between voltage and current, and the fact that resistance is simply the slope of that relationship, is so ingrained by now, that I don’t even think of Ohm’s law as something distinct from the essence of electricity. Same for Kirchhoff’s laws – and the water analogy which works so well in so many cases to match intuition to the real world.

So the Easy Electrons series was born – no math, no theory, just a set of posts which tackle a number of electronics concepts in what I hope can bring across some of that intuition. My drawing tools at the time were based on paper and a scanner, so the drawings were a bit crude and hard to read – here’s an example where I’m trying to explain how to drive LED strips which draw more power than the weak I/O pins of an ATmega can provide:

There are posts about voltage and current, about power and heat, about resistors and capacitors, about LEDS and diodes, and about transistors and MOSFETs, to name a few.

Don’t take my word for it, heck… don’t even read my posts if you don’t want to – all I can say is: if you ever hook up electronics circuits of your own imagination and invention: get to grips with the basics, so you’ll understand why hooking up a bunch of LEDs in parallel is usually not such a good idea, why using a power supply with a higher voltage is likely to lead to overheating and damage, and why hooking up relays and motors often requires extra protective circuitry.

It’s not hard, it’s not magic, it requires no math of any sophistication (and there’s always the brilliant Khan Academy if you want to brush up on it anyway). It can be exhilarating to be able to design and predict what a circuit will do before hooking anything together.

Electronics is a truly wonderful field to explore (and it’s huge!). You don’t need much to experiment with, and you will learn a lot – if only to become quite respectful of the laws of physics, which are merciless (still: most mishaps are harmless and nothing gets damaged).

You’ll run into everything from “nothing happens” to “it’s smoking”, and it’s terrific fun!

1. Although I was also “into” electronics from an early age, have to say that I work with some clever people who cannot grasp the concept of electricity, no matter how I try to explain it. Also I tend to find that my electrical colleagues can grasp concepts in other disciplines without too much trouble but it doesn’t always work the other way around.

2. Your last sentence reminds me of a @jeriellsworth tweet yesterday: “I don’t think my boost converter circuit should be smoking right now. Interesting.”