circuit pathways?

[johnnym]

Do any of you have a suggestion on understanding circuit schematics for a newb? I understand them somewhat and have taken a basic electricity course at a trade school (I got a B in the class, lol) but still don't fully understand. I have done many beginner arduino projects like the solar tracker, ldr lighting, the knight rider, you know, shiite like that. Really basic stuff. I want to be able to look at any schematic and know how to put it together in my mind (if parts were imagined or real and still be able to tell that the circuit would work)....    So many of you on this forum know how to do just that. Failing over and over again has been my best teacher but a more efficient way has to exist. Can anyone explain how to follow circuit pathways in more detail? I don't know if this makes any sense and tend to overthink things. Any input would be appreciated. This forum is great. In fact, I have learned more here than that basic electricity class I took.

[clockmanFRA]

Hi johnnym,

I learnt most stuff from doing those Heathkits. Maplin, velleman etc

You know, make a basic radio etc.

In those days you just got a bag of components, PCB, Schematic drawing and some notes. I used to spend hours just working out what was what and its value.

Nowadays the Internet gives you a fantastic resource without the need for a physical library of books/and application notes, that showed chip pin outs and what did where and to whom etc.

https://www.amazon.co.uk/9088-Tuner-Electronic-Components-szsp13/dp/B000CJVZ0I/ref=sr_1_fkmr1_2?ie=UTF8&qid=1537950805&sr=8-2-fkmr1&keywords=Vellman+electronic+radio+kit


Hmm thinking about, I am not a very good example of knowing what I am doing. But others here have very large brains with great knowledge.

[OperaHouse]

I still think failing is the best teacher. We tend to learn a small detail and expand upon that in our mind with an answer that fits our understanding.  I can tell you how to select a FET, but many will see that 75A rating on a FET, want to use it 20A and think they are home free.  I can't tell you how to think like an electron, they always know what they are supposed to do. Follow a current path and ask yourself why is that component there. Like the KAHN method, make sure you can answer that before advancing. I still often see things that can't be initially explained.  Be assured that the laws of physics have not changed.  I had a new 300K 1W resistor from a top manufacturer fail in a 12V circuit. All my experience told me that was impossible and I couldn't accept it Software is extremely unforgiving and sometimes difficult to see.  Mathematical = and logical == are not interchangeable. Think of an arduino project and lets work on it.

[SparWeb]

I could recommend the books by Forrest Mims, and websites like All About Circuits, but I bet you already saw the thread a couple of weeks ago when I recommended that before.

Here's another way to look at a circuit (this example is DC):
Start at the +V supply, whatever it is, and then look for the ground, wherever that is.  Some circuits don't draw the trace all the way back to the negative battery terminal, so anywhere you see the three horizontal lines, you have to take that as ground.  For each path you can find from the + to the - imagine a current flowing.  On any given path, there could be a bunch of components, and these will decide how much current can flow through that path.  If a path has lots of resistance, or something like a capacitor in line, then there probably isn't much current flowing on that path.  There are probably many paths.  You could follow all of them, but before giving yourself a headache, look for the ones that use the most current, meaning, the least resistance.  That gives you an idea how much power the whole thing needs.  Next, follow the power to some of the devices, like relays, IC's, motors, etc.  Often these get power all the time, but some of these get switched on/off by other things on the circuit.  Noticing that, you can tell how one thing controls another thing.

Yeah, hard to know where to start, but if you start by looking at a little piece, figuring that out, then looking at how the next pieces attached to it work, you can start to draw the big picture.

[Mary B]

Not to bad of an intro to reading schematics https://learn.sparkfun.com/tutorials/how-to-read-a-schematic plus it has links to other resources.

[frackers]

After the usual making of crystal sets winding coils on a cardboard toilet roll, I progressed to the Philips Electronic Engineer kit - somewhere about 1963/4. If you look at the pictures on-line   

   

you'll see how clever it was with a piece of card with the schematic on it, a hole at each junction with a spring clip that held the components with a few connecting wires. No PCBs, no soldering and a range of projects to play with from flashing lights and beeps to radios.

I doubt that anything like this is available now but take a look at some of the images and you'll start to see the relationship between component and schematic and what makes the whole circuit work.

[OperaHouse]

That reminds me of what I saw a while ago.  The guy just drew a big schematic and attached it to a piece of cardboard.  Then stuck an ice pick where the components went. It made understanding the schematic easier.  No need to convert thought from schematic to wiring.  Doing the same thing to a wood board with screws would work in place of springs.

[Mary B]

One of my early projects was like this one. Simple 1 tube CW transmitter to go with the cheap shortwave receiver I had.

[OperaHouse]

Some of the best videos for understanding electronics are on EEVblog.com and they are also entertaining.  They explain the basics and advanced considerations at the same time for each subject.

[johnnym]

Cool, thanks every one. I think someone should write a "Electronic Circuits for Dummies" book.

Ok, after typing that last sentence I decided to look it up and someone or some company did write such a book.

 The pictures of the old school examples are very cool. Like a simplicity to it.