Making a conceptual leap in electronics

Thread Starter

pathos

Joined May 24, 2013
12
Hi Folks,

I'm in the biol/medical field and a longtime amateur radio op. I have a good basic understanding of passive components and getting there in digital. However, after this point, trying to understand the flow of currents, presence of and location of voltages, etc., in a pragmatic circuit or how to " see" the function of a particular circuit or use of a particular component within a circuit, has left me in the dark to a large degree. For instance, the use and how to place a coupling capacitor and how to pick the right type of capacitor and the right value, why provide feedback from the agc circuit in an am radio to the first IF amplifier and how to put the circuits together, or why place a resistance here or there ( except in the most basic of circuits- rf oscillator, etc), . It seems to me that the is a missing component of my study of electronics, that allows me to make this conceptual jump and ultimately reach my goal of building or designing circuits or components , that are useful in building larger components or radios, especially related to amateur radio. I'm looking in Grob's electronics today. Any suggestions on how to approach this gap in my education? Thanks in advance for any advice. Dr Dave, WS0D.
 

nsaspook

Joined Aug 27, 2009
6,883
The conceptual leap in electronics understanding IMO is to see that electronics is just a technology (machinery) of electrical science. Electronics is a means to the end of controlling electrical energy for work (the physics meaning) and that usually means understanding basic engineering mechanics because electrical phenomena is usually described today in a way that's compatible with the principles of machines. First look to see how the energy/power moves, what happens at each stage with that energy and what components within a stage that make it happen in the proper order just like you would for any complicated machine.


This seems very abstract and distant from electronics at first because we don't see little gears and levers moving in a radio but the mental images of energy machines provides a useful framework for the brain to visualize circuits with practice.
 
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#12

Joined Nov 30, 2010
18,190
The, "conceptual leap" happened for me after 4 years of 40 hour jobs working on electronic circuits. The, "light bulb in my head" went on.:)

Maybe I'm slow, but that's what I required to go from, "I'm supposed to know the math" to, "I can count every microamp in that circuit and know why it's there and which way it's going." This would seem to say that experience is important. After 50 years of this, I have a lot of circuits in my head, along with the characteristics of several kinds of capacitors, how temperature changes component performance, what kinds of interference are lurking just outside the box full of circuits, when it's important for components to match each other....

Working from the theory of brain plasticity, it takes time to form the connections, and there are a lot of connections to be made!
I think the basic theory of school education is: Tell them everything once and they will figure out how it all fits together, eventually."
In the real world, some kinds of problems happen a dozen times a day and some come up every few years.
If you can read the books once and know how it all fits together, you're a better man than I, Gunga Din!

Of course, this is only my opinion. Your mileage may vary.
 

MrAl

Joined Jun 17, 2014
7,093
Hi Folks,

I'm in the biol/medical field and a longtime amateur radio op. I have a good basic understanding of passive components and getting there in digital. However, after this point, trying to understand the flow of currents, presence of and location of voltages, etc., in a pragmatic circuit or how to " see" the function of a particular circuit or use of a particular component within a circuit, has left me in the dark to a large degree. For instance, the use and how to place a coupling capacitor and how to pick the right type of capacitor and the right value, why provide feedback from the agc circuit in an am radio to the first IF amplifier and how to put the circuits together, or why place a resistance here or there ( except in the most basic of circuits- rf oscillator, etc), . It seems to me that the is a missing component of my study of electronics, that allows me to make this conceptual jump and ultimately reach my goal of building or designing circuits or components , that are useful in building larger components or radios, especially related to amateur radio. I'm looking in Grob's electronics today. Any suggestions on how to approach this gap in my education? Thanks in advance for any advice. Dr Dave, WS0D.
Hello there,

What you seem to be asking about is how circuits work and how to design circuits that you would like to create that maybe were never even created before or you just want to be able to roll your own.
This is a little different than pure physics, where you might want to analyze matter itself and its relationship to electronics and use it in constructive ways that are particular to electronics.

Either way though the usual procedure is to learn how to analyze circuits first, then later how to design them. This is mainly because you want to be well grounded in how circuits work before you start to try to design anything new, and analysis tells you how circuits work.

A large part of circuit analysis falls into the category of lumped element theory, where you treat each component as a physically complete object which already has a complete electrical specification with a set of parameters. Knowing those parameters alone allows you to analyze circuits as well as design circuits without knowing the exact physical construction. In some cases the physical construction becomes important, but then usually there is a theory to go along with that already that you apply and come up with some results. There will also be times when you have to dig into the describing PDE's but you can go pretty far without that too because there are many approximations that are assumed good enough in all but the most stringent case.

So a good starting point is to find an analysis method you like, or study several analysis methods. One popular method is Nodal Analysis and it's not too hard to learn. The basic form uses simultaneous linear equations to come up with node voltages and branch currents. That gets you pretty far because this can be applied to a large number of circuits. I would bet that you would actually find this too easy :)

Once you learn that, which wont take you long, then you can start to analyze circuits that you are interested in and once you do a number of circuits you'll start to get ideas how to design your own.

Minimum math prerequisites would be algebra, trig, geometry, calculus, differential equations, but it depends how far you want to go too. Also, there are free simulators available like LT Spice where you can check your results to make sure you are doing it right. So you could learn a huge amount without ever asking another question (except maybe how to use the simulator maybe).

As far as voltage and current goes, voltage is an 'across' variable and current is a 'through' variable. That means a voltage will be measured between two points and a current with be measured as flowing through an element. Usually a voltage is measured across an element in lumped theory. That means for any given two terminal element you will see a voltage across it and a current through it.
Voltage is often measured between some point of interest and a node called 'ground' which is a zero volt reference point. Thus if you measure 5v at point A and 6v at point B, that means the voltage at point B is 1v higher than at point A.

It also helps to have at least one multimeter so you can start to make some actual measurements and get some hands on experience with components.
 
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crutschow

Joined Mar 14, 2008
24,291
Knowing advanced mathematics is good, but it's not necessary for a basic understanding of electronics.
You can do quite a bit with just basic arithmetic and algebra. You should, in particular, learn phasor algebra and how it applies to AC circuit calculations.
Nodal analysis is good to know, but it's not necessary for the study of most practical circuits.
You certainly need a good understanding of how resistors, capacitors, and inductors behave when AC or DC voltages are applied across them.
Study resonant RLC circuits, both serial and parallel, and how the value of each component affects the resonant characteristics.
Learn how to calculate the equivalent value of series and parallel circuits, including resistive, capacitive, and inductive combinations. This will involve phasor algebra.
Become familiar with the operation of FETs (both MOSFETS and JFETs) and bipolar junction transistors (BJTs).
Learn how op amps work and the use of negative feedback with them.

As can be seen there's likely a lot to learn before you reach the "eureka" moment.
And as MrAl noted, a circuit simulator such as the free LTspice from Linear Technology which several of us use on these forums, can be quite useful for easy experimentation with circuits without having to build them physically. That makes it easy to check your understanding of circuit operation.
It has its limits, primarily based upon the accuracy of its models, but usually if the simulated circuit does not work, then the actual one won't either.
It has a somewhat steep learning curve, but there is a tutorial and many simulation examples to help you get started.
 

MrChips

Joined Oct 2, 2009
20,156
I don't know at what point in my life I crossed the threshold from darkness into light with respect to understanding electronic circuits. What I do know is that from the early age of 15 years I spend most of my awake hours pouring over the pages of magazines such as Practical Wireless and Popular Electronics from cover to cover multiple times while eagerly waiting for the next month's issue to arrive.

Then I moved on to acquiring various texts and books from such gurus as Clive Sinclair, Forrest Mims, Don Lancaster and numerous TAB books on 101 Electronic Projects.

My suggestion would be to look at other people's circuits and try to read and follow the description on how they work.

Here are some electronics sites as examples of what can be found online:

Tony van Roon (deceased 2011)
Elliot Sound Products
http://www.discovercircuits.com/
 

Papabravo

Joined Feb 24, 2006
12,847
For me it was understanding that a TTL input sourced current and that a TTL output could sink current, but could only source a very little bit. After that it was down the potential hill all the way.
 

AlbertHall

Joined Jun 4, 2014
9,249
How to learn? MAKE MISTAKES and then learn from them. Just be sure that the mistakes you make are not life threatening.

I was learning electronics before the ubiquitous computer appeared. My local library childrens' section had a remarkable selection of books on model making and radio control and I learnt loads from there while still in primary school. There was no LTspice or solderless breadboards so my mistakes were made with real components. I saw that a transistor was equivalent to two diodes back to back and I was most disappointed when my two diodes didn't amplify anything. then I went back to the books to find out why.
 

BR-549

Joined Sep 22, 2013
4,938
Get a handful of digital chips. Get 2 handfuls of analog components. Get a breadboard, power supply, and a two channel scope. And you have the internet. You're all set.

Play.
 

Thread Starter

pathos

Joined May 24, 2013
12
Hi Folks, thanks to all. I think all replies have hit upon various aspects of my dilemmas. When I first got my amateur license in junior high school, I was reading all I could about electronics and spent most my time putting together Heathkits (when my paper route allowed me) or experimenting with antennas. I was bright enough at that time to keep my hands out of the radio when it was tuned on, but really didn't get to do much more. Then life happened, and now some 40 years later, give or take, I've gotten more interested in understanding the circuits and building/modifying them. I've got a pretty good hold on passive components and basic digital, and have spent some time with circuit analysis (Thevenin, Wye, etc- very superficial). Today, as I was soldering an old kit together, I had the old
Air Force Tutorials on Electronics on in the background. Yep, there is alot out there. But as folks above had said, I'm betting that it going to take some time, just messing with the circuits, whether physically or virtually with LT Spice, to get to an AHA! moment of understanding how things mesh to get a functional (or useful or working) output. Thanks again to all that have responded and I hope to be chatting with you all in the future. Dave
 
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