Ask HN: What are some good resources to learn how electricity works? • Hacker News Board

Re: Ask HN: What are some good resources to learn how electricity works?

#71

Post by sunstone » Thu, Jun 18, 2020, 2:39 PM UTC

dannypgh wrote: post #20

I would suggest things that use the hydraulics analogy, like this: https://ece.uwaterloo.ca/~dwharder/Analogy/

I would probably recommend this. Thinking of electricity as analogous to water flow under gravity can get you a long way. I do recommend studying the mathematics of imaginary numbers (not hard, just takes a bit of time) since this is used for AC circuits and this is the tool that makes that stuff make sense.

When you get to active (transistors, diodes etc) devices don't spend much time trying to figure out the physics of these things just use the equations and keep it simple. Just as when you're cooking eggs in the morning it doesn't help much to understand prospecting, mining and metallurgy to use the frying pan.

Re: Ask HN: What are some good resources to learn how electricity works?

#72

Post by mjoin » Thu, Jun 18, 2020, 2:39 PM UTC

mjoin wrote: post #61

basjacobs wrote: post #47

I highly recommend the All About Circuits textbook: https://www.allaboutcircuits.com/textbook/ It starts from the very basics and builds up to quite complex circuits and their workings. It's an all-round great website, too.

this looks very good. do you know if there is a PDF version that contains the whole textbook? could not find it on the website

actually found the PDFs

Re: Ask HN: What are some good resources to learn how electricity works?

#73

Post by spiralganglion » Thu, Jun 18, 2020, 2:44 PM UTC

Buttons840 wrote: post #67

Follow-up question: How do I safely experiment and play with my newfound amature electrical knowledge?

I'm a musician, so my inroad to safely playing with electronics was circuit bending. You can buy kid's toy pianos and soundmakers and such for effectively $0 at thrift stores. Unscrew the casing, crack it open, pop in fresh batteries, get the thing making some its sounds and then.... start bridging together different locations on the circuit board and see what the effect is! I've often been amazed what sort of beautiful, otherworldly tones you can pull out of something that would otherwise be seen as near-garbage. Because it's battery-powered, the risk of shock is really low. It's a way to play with circuitry without inhaling a bunch of solder fumes. It's fun to do with kids. You can do it with pretty much any circuit that makes sound (even those greeting cards that play music when you open them). Lastly, there are a ton of resources online if you aren't quite sure what to do — the term is "circuit bending", it's great, have fun!

Re: Ask HN: What are some good resources to learn how electricity works?

#74

Post by stx » Thu, Jun 18, 2020, 2:45 PM UTC

Buttons840 wrote: post #70

athenot wrote: post #68

Earlier quoted context omitted.

Stay with low power. (Low tension and low intensity.)

How? Use batteries only? Obviously I shouldn't plug my own creations directly into the wall. Is it safe to use a low voltage "power brick"? Will any do, or do I need an especially robust one just in case?

As a kid I played with batteries and wall bricks or wall warts or whatever you call them(transformers). I would not say you need an especially robust one. They come in different sizes based on the amount of voltage they output and the potential current they can supply. Basically if you are playing with a 9 volt battery and want to replace it with a transformer just look for one that says 9v DC output on it.

Re: Ask HN: What are some good resources to learn how electricity works?

#75

Post by senderista » Thu, Jun 18, 2020, 2:46 PM UTC

samjohnson wrote: post #39

projektfu wrote: post #36

I remember in high school I had trouble getting it because I thought ohms law had too many variables. Then I realized that a 5V supply will always be 5V in normal operation and ohms law means the current varies. All of the water analogies were unhelpful for me. I did better just doing the math and seeing the result. Someone else mentioned MITx. I did that and it was revolutionary. I also have a pretty good book calle…

> Then I realized that a 5V supply will always be 5V in normal operation and ohms law means the current varies. This is a great observation. I've often thought that teaching Ohms law as I=V/R would lead to less confusion. Similarly, in intro physics why is mass acceleration introduced as f=ma? Wouldn't a=f/m have a clearer meaning?

I agree, that’s my preferred form as well. That’s because Ohm’s law is an empirical law, which states that current is proportional to voltage. It’s the definition of resistance, and it’s not always valid.

Re: Ask HN: What are some good resources to learn how electricity works?

#76

Post by randylahey » Thu, Jun 18, 2020, 2:50 PM UTC

basjacobs wrote: post #47

I highly recommend the All About Circuits textbook: https://www.allaboutcircuits.com/textbook/ It starts from the very basics and builds up to quite complex circuits and their workings. It's an all-round great website, too.

Wow, I'm so happy to see this is the first result (the reason I came to comment.) I've tried and failed many times to pick up a fundamental, from the ground-up understanding of electronics and electrial theory. Forrest Mims' "Getting started in electronics" was good, but the All About Circuits text book had the depth and accessibility and I was looking for.

And it's free!

Re: Ask HN: What are some good resources to learn how electricity works?

#77

Post by stx » Thu, Jun 18, 2020, 2:51 PM UTC

ar0b wrote: post #30

I had an electronics learning lab from radio shack and loved the hands on aspects. https://www.amazon.com/RadioShack-28-280-Electronics-Learnin... You can still find them on ebay, or similar kits if you look around.

I had these as a kid but in reality at the time I think I was too young to understand the details of what was going on. Many of the components I would accidentally attach a large battery to and let the magic smoke out. I do miss Radio Shack though.

Re: Ask HN: What are some good resources to learn how electricity works?

#78

Post by TacticalTable » Thu, Jun 18, 2020, 2:51 PM UTC

Buttons840 wrote: post #70

athenot wrote: post #68

Earlier quoted context omitted.

Stay with low power. (Low tension and low intensity.)

How? Use batteries only? Obviously I shouldn't plug my own creations directly into the wall. Is it safe to use a low voltage "power brick"? Will any do, or do I need an especially robust one just in case?

I recommend playing with 5V, many Arduinos and microcontrollers run on that, or have a voltage converter that allows them to accept it. And this means you can use a stripped USB cable from a standard usb wall plug to power your projects.

Re: Ask HN: What are some good resources to learn how electricity works?

#79

Post by gorpomon » Thu, Jun 18, 2020, 2:51 PM UTC

spiralganglion wrote: post #69

I'm the solo dev on an industrial training website. We have a short lesson about the basic electrical units (voltage, current, resistance) that might serve as an approachable introduction or handy reference: https://www.lunchboxsessions.com/materials/basic-electrical-...

Your site is really amazing. Well done! I was a mechanical engineer for a bit and it's fun going through your lessons and reacquainting myself with that world.

Re: Ask HN: What are some good resources to learn how electricity works?

#80

Post by stx » Thu, Jun 18, 2020, 2:54 PM UTC

stx wrote: post #74

Buttons840 wrote: post #70

Earlier quoted context omitted.

How? Use batteries only? Obviously I shouldn't plug my own creations directly into the wall. Is it safe to use a low voltage "power brick"? Will any do, or do I need an especially robust one just in case?

As a kid I played with batteries and wall bricks or wall warts or whatever you call them(transformers). I would not say you need an especially robust one. They come in different sizes based on the amount of voltage they output and the potential current they can supply. Basically if you are playing with a 9 volt battery and want to replace it with a transformer just look for one that says 9v DC output on it.

There are people who say things like its not the voltage that kills its the current but through the human body under normal conditions it takes a decent bit of voltage to induce enough current to really hurt you. Watch out for things with large capacitors and large voltages. If you want to take something like that a part let it sit for a long time for the capacitors to discharge. I worked at a TV repair shop in high school dismantling tube TVs for scrap components. The first step after opening was to use a large screwdriver to discharge the flyback transformer.