[NOOB] Understand electronics jargon (need some guidance))

Hello all,

So I'm very recent to Arduino. I've bought my starter kit for about a month ago and I've recently finished the book. For the most part, I really liked it, although my main issue is that, the book did not give (or a clear enough) explanation (with sufficient examples) certain topics. With that said, I really enjoyed doing the tutorials. I've learned a lot. Coming from a programming background it made my experience even more enjoyable. Still I have a very blurry understanding in the following topics:

  • When/Why to use capacitors and how to calculate it (Project 05 - Mood Cue, it is given a short explanation, but why the 100uf ? What does it mean ? How is it calculated ?)

  • The same goes for resistors. I did a quick test with only a button connected to the arduino to track the value of the button via SerialMonitor. I though noticed that when pressing and releasing the button, I was getting unexpected values and the output was behaving erratic. I then read online that a resistor is needed due to current fluctuation or something.

  • Another part that, because I'm a noob in this, I still did not get a good understanding of the concept of Voltage, Current and Resistance. Also, that voltage is measured in amps ?!

Could the community provide with some useful guides on understand the above mentioned concepts ? I did watch some videos and read some documents on it, but things get confusing really quick.

Maybe this: https://www.instructables.com/Basic-Electronics/

But what you're really looking for is a decent Electronics 101 course or a book aimed at absolute beginners. I can't help you with that; maybe something like this: https://www.amazon.com/Understanding-Basic-Electronics-Softcover-ARRL/dp/0872590828
There's probably a few thousand similar books that try to achieve the same goal of explaining the fundamentals of electronics engineering to people - finding a good one will be the trick.

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The resistor is to "pull down" the output of the button to stop it "floating" and providing inaccurate results.

The relationship between Voltage, Current and Amps in a circuit is given by ohm's law: V=IR
where "I" is current, "R" is resistance and "V" is voltage.

Not that there is anything wrong with asking the community, but in this case you may want to put a solid base to your future understanding and read a good book on the subject.

Maybe my message can be a bit deceptive, what I actually mean is that if the community can provide me some guidelines on where to start, ie: point me to good resources (books, articles, user manuals, or even explain here).

Hope this clarifies it.

Simon Monk has written a number of Arduino books and he also collaborated on a book called "Practical Electronics for Inventors" which is well reviewed on Amazon. It looks like it covers everything you're looking for (and a great deal more).

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Outstanding resource: The Art of Electronics, by Horowitz and Hill


While an excellent book I believe that The art of electronics is a bit too much as an introduction.

Just a couple of quick comments...

If you were taking a class in electronics the 1st thing you learn is Ohm's Law which defines the relationship between voltage, resistance, and current (Volts, Ohms, and Amps). In the 1st semester you'd learn about how all of this works in series and parallel circuits and you might learn about using capacitors and inductors in DC circuits. Capacitors and inductors are more "interesting" in AC circuits but that would probably wait 'till the next semester.

There is a "standard water analogy" where water pressure is voltage, water-flow is current, a skinny pipe is high resistance and a fat pipe is low resistance. (Electrical resistance is the resistance to current-flow.) The main difference is, if you cut a pipe you get zero resistance and water flows-out all over the place. If you cut a wire you get infinite resistance and no current flows. Also, nothing bad happens with zero water resistance (except maybe a flood. :wink: ) but zero electrical resistance is a "short circuit", you get excess current and you can burn-up a power supply or blow a circuit breaker, etc.

The "trick" is knowing when the value is critical and when it's not. That only comes with learning and experience. Most of the time the value is not critical or "bigger is better". Sometimes the type of capacitor matters... Electrolytic capacitors (most 100uF are electrolytic) don't "act like" capacitors at high frequencies. For that reason, sometimes you'll see a 0.1uF ceramic capacitor in parallel with an electrolytic.

It's like what size nail or screw should you use? If you're building a bridge you have to calculate the stress on every bolt and use the right size and the right material but if are building something yourself you just choose a nut and bolt that seems "about right". The same goes with resistors and something like a pull-up or pull-down resistor can be between 1K and 10K, and even beyond that range in many cases.

A capacitor can hold a charge (a voltage) something like a battery. This is a simplification, but when I was first learning electronics I was told "capacitors resist changes in voltage" and "inductors resist changes in current." It also depends on if they are used in series or parallel... And in-series, "capacitors block DC current flow" but "pass AC".

When an Arduino input isn't connected to anything it can "float" to an unknown voltage and read high or low. The resistor "pulls-up" or "pulls-down" the input. (Pull-ups are more common in digital electronics.) When the the button/switch is activated (closed) the switch "overpowers" the resistor, a state-change is "forced" and current flows through the resistor. In this particular case, the current doesn't serve any useful purpose... It's wasted energy but that's what happens when you "overpower" the resistor (or whenever you apply a voltage across a resistor... Ohm's Law).

A pin configured as output will NOT float. So if you connect the output of one Arduino to the input of another Arduino, you don't need a pull-up or pull-down.

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There are many uses of capacitors, without a link to the Project 05 you mention I don't know which use is relevant. Capacitors are used to couple, decouple, provide time delays, do signal filtering, store energy, etc etc.

The inputs of a CMOS logic chip have (nearly) infinite resistance - this means the voltage is not well defined unless they are connected to something - with a push-button switch that's open-circuit you need some way to define the voltage (stop it floating). Floating inputs are very very sensitive to nearby signals through coupling due to leakage and stray capacitance. A resistor of a few kiloohms defines the voltage nicely, yet doesn't lead to a short-circuit when the switch is operated.

Voltage is the energy per unit charge, current is the flow of charge per unit time, resistance is voltage/current. Voltage ("electrical potential difference" is the formal name) is measured in volts, current in amps.

One volt is one joule per coulomb, one amp is one coulomb per second. The coulomb is the unit of charge, 6.2 million million million electrons together have a charge of about -1 coulomb.

You can use the fluid-flow analogy, current is equivalent to volume flow, voltage to pressure, resistance to flow-resistance.

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Yes of course there are thousands of offerings.

When I was studying I used this method to find material that made it it easy to learn:
of course I started with the recommendation of the professor but I put the books to the following test:

I took one chapter of interest and started reading. If it was easy to understand I continued to read at least two pages to see if I can undestand almost everything.
If not I put the book back on the shelf taking the next one doing the same test.

Sometimes it took me 20 books until I found one that was easy to understand. But it was always worth the time to read 19 times 2 pages to finally find the one really good book.

Today you have all this youtube and online stuff.
Well the same basic principle canbe applied: start watching a video
If you recognize the guy in the video uses words you don't know yet - skip this video.

The maker of this video has not thought carefully about how to start explaining with everyday words to make it easy to understand and to build specific terms onto each other.

Build specific terms onto each other means the first specific term should be explained in everyday words and then introducing the new term. If the teaching goes on the new introduced term can be used to explain a second specific term etc. etc.

So you simply watch a video maybe 30 to 60 seconds and if you have already lost understanding
just skip this video / the website - whatever it is the bad explaining style will go on.

Some comments about websites I can across
practcial instructions without explaining the theoretical backround

online simulation for circuits where you can modify a lot of parameters to see what effect they have on current, voltage, resistance.
You can even put the voltage to 100.000 Volts to set everything on fire. (really the components will burn virtually on the screen)

This video explains basic concepts of electricity with the water-analogon

or this one

Your question "why 100µF" What does it mean ?
Explained on the surface:

it as a number for how much "electricity" the capacitor can store. Bigger number bigger capacity

"How is it calculated ?" to explain that goes truely deep into a lot of different aspects of electronics. So just take the number and some rules of thumb.

best regards Stefan


100uF is 100 microfarads, and a one farad capacitor stores one coulomb per volt, so 100uF stores 100 micro coulombs per volt. In the fluid flow analogy its like an elastic diaphram across the pipe.

perhaps go to your local library and see what they have in the way of basic electricity books.

I've been searching more for some videos and came across this one: Lesson 1 - Voltage, Current, Resistance (Engineering Circuit Analysis) - YouTube

He explains it really well all the general concepts. Video quality is not the best but the content is superb.

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