Yes on the first two, and I'll take a rain check on the third; I think I'm a long way away from being able to deal with logic circuits right now. Honestly. I looked at the circuit for the Hafler Iris preamp, which is a rats nest of op amps. Then I looked up all the op amp types. I understood immediately what each one of them did. Then my brain tried to make sense of how any of that could possibly be useful in a circuit, and it convulsed and went into its happy place.
I learned a lot of my basic electronics from the ARRL's Radio Amateur Handbook. It came out each year updated, bless them. LAte 1950s and early 1960s were my favorites, covered tubes well. I have a 1962 somewhere that is totally worn out. That and my RC28 RCA tube manual. Lots of tutorial chapters in that.
But in my professional life I have been responsible for technician training and support at a couple companies. And teaching troubleshooting, I have learned there are many ways to convey all this. And I liked learning as many as I could. WHen I have a pupil not connecting, I try a different approach. If I have ten books on a topic, I know some of them will not communicate with some individuals, but some others will. I keep trying until I find a book or a way that speaks to that individual.
SO when you read books, if one doesn't speak your language, put it aside and try another. That first one might make perfect sense in a year, but not now. What works for one may not work for another, and vice versa.
But in my professional life I have been responsible for technician training and support at a couple companies. And teaching troubleshooting, I have learned there are many ways to convey all this. And I liked learning as many as I could. WHen I have a pupil not connecting, I try a different approach. If I have ten books on a topic, I know some of them will not communicate with some individuals, but some others will. I keep trying until I find a book or a way that speaks to that individual.
SO when you read books, if one doesn't speak your language, put it aside and try another. That first one might make perfect sense in a year, but not now. What works for one may not work for another, and vice versa.
I just decided to check with the local technical college, as well as the larger state college about half and hour from here. All of the electronics classes are gone along with the programs they populated. There was nothing at the tech school, and all that remained in the catalog at the state college was a pair of courses: "Introduction to Electronics" and "Solid State Electronics". By using the search feature I found two more classes which I guess they'd forgotten to delete from the catalog, but still existed in the database: "DC Circuit Analysis" and "AC/DC Circuits".
This is wow... has there been such a lack of interest in electronics knowledge these past few years that schools no longer teach it?
This is wow... has there been such a lack of interest in electronics knowledge these past few years that schools no longer teach it?
@JMFahey has it right, at least so far as the way I learn. The old books are the best. The college texts from the 1940s to maybe the 1970s. I suck at math and the math is understandable. At some point they went all calculus and matrix and lost me. Those older books are written for somebody that will have to design or fix things. Sure, no opamps, but you need the fundamentals first. In fact, you can never go wrong by reviewing fundamentals- I do it quite often. Everybody should have a Terman, a middle (5th) edition Boylestead, maybe an old Timbie & Bush set and certainly a measurement book like Stout or Harris. Read all Jim Williams app notes. Read Bob Pease (What's all this xxxx stuff?) Hey, I started out with batteries, small bulbs and sockets, knife switches and bell wire, but LTSpice is way easier. As far as amplifiers, signals don't actually go anywhere. They wiggle something that causes current to flow. That wiggles something else that causes another current to flow, and so on.
My advice is to start at the beginning.
The GFA-535 is not a simple circuit and if you do not understand how a basic transistor functions, you will not be able to fully grasp what is going on inside that amp.
Taking classes is a good idea but not always easy to do. Instead, I suggest you jump on youtube and watch some of the many electronics fundamentals courses. Try some of the simple and popular ones like GreatScott and BigCliveDotCom and then as you get the grasp of each fundamental puzzle piece, move into more advanced offerings. There are many offerings at many levels - don't be afraid (or ashamed) to start basic. Treat it as learning a new language - you're not gonna be writing a thesis without a vocabulary and grammar.
Before you start with LTSpice, get something like TinkerCAD and just mess around with basic circuits. As you get a little more familiar, move onto LTSpice but copy simple circuits. Play with them. Build an RC filter. Build an emitter follower. Built a bridge rectifier. Adjust the components. See what happens. Learn by exploring.
As you start to grasp the physical fundamentals, start to fill in the blanks with the Math. Why does a resistor divider work? How can I calculate the voltage from a given ratio? How can I calculate what resistors I need from what goes in and out? Later on, subscribe to a free OpenMIT electronics course.
Forget poor analogies such as water wheels and understand what is actually going on. For years of Uni I was taught that a transistor is 'just 2 diodes connected together' and I could never really grasp what was actually happening or why. Then eventually I binged on instructional videos until I truly understood what was happening and why. Then moved into the more advanced math based lessons to find out what was really going on. I then moved into topologies starting with the most basic - using a transistor as a switch.
Anyone can learn anything with enough practice and persistance.
Good luck!
P.S. The Art of Electronics is a good book, but not really easy for beginners. If textbooks are your thing, start with something like 'electronics for dummies' or suchlike to get a basic spoonfed introduction. Get the AoE later, when you're thirst for knowledge exceeds the basic fundamentals. I bought the latest version and don't regret having it as a reference.
The GFA-535 is not a simple circuit and if you do not understand how a basic transistor functions, you will not be able to fully grasp what is going on inside that amp.
Taking classes is a good idea but not always easy to do. Instead, I suggest you jump on youtube and watch some of the many electronics fundamentals courses. Try some of the simple and popular ones like GreatScott and BigCliveDotCom and then as you get the grasp of each fundamental puzzle piece, move into more advanced offerings. There are many offerings at many levels - don't be afraid (or ashamed) to start basic. Treat it as learning a new language - you're not gonna be writing a thesis without a vocabulary and grammar.
Before you start with LTSpice, get something like TinkerCAD and just mess around with basic circuits. As you get a little more familiar, move onto LTSpice but copy simple circuits. Play with them. Build an RC filter. Build an emitter follower. Built a bridge rectifier. Adjust the components. See what happens. Learn by exploring.
As you start to grasp the physical fundamentals, start to fill in the blanks with the Math. Why does a resistor divider work? How can I calculate the voltage from a given ratio? How can I calculate what resistors I need from what goes in and out? Later on, subscribe to a free OpenMIT electronics course.
Forget poor analogies such as water wheels and understand what is actually going on. For years of Uni I was taught that a transistor is 'just 2 diodes connected together' and I could never really grasp what was actually happening or why. Then eventually I binged on instructional videos until I truly understood what was happening and why. Then moved into the more advanced math based lessons to find out what was really going on. I then moved into topologies starting with the most basic - using a transistor as a switch.
Anyone can learn anything with enough practice and persistance.
Good luck!
P.S. The Art of Electronics is a good book, but not really easy for beginners. If textbooks are your thing, start with something like 'electronics for dummies' or suchlike to get a basic spoonfed introduction. Get the AoE later, when you're thirst for knowledge exceeds the basic fundamentals. I bought the latest version and don't regret having it as a reference.
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Any of the Nelson Pass ACA type designs are excellent to learn the ropes. They are straight forward, you can build them yourself, they have not too many parts and there's excellent write-ups available.
A good place to start.
And don't get hung up on electron flow direction. Not at all necessary to understand circuits. Just consider current from + to - like water flow, and you're home free.
Jan
If I may, a word of advice from someone who graduated from a good college in the early 70s with a major in physics, straight into the teeth of a recession where some form of electronics was the only work option. Outside of the math background I was as puzzled by it as anyone. So I took a night course at a local college in Circuit Theory 101/102. Then I went back to school at another good college for... what else... physics.
When I emerged with an MS into the same recession it was on to the minicomputer industry. That's all there was. There I found myself immersed in EEs (NOT educated as digital designers, not back then... they were still inventing what would be taught in later curricula) and found that 90% of my practical electronic knowledge had come not from those two good colleges but from the night course in Circuit Theory 101/102. That and my ill-funded hi-fi hobby.
Few translate E-M physics into electronics on the fly. The applications, shortcuts, tricks and abstractions have already been done (and learned by the EEs that surround you). Simply accept Ohm's Law and its variations and derivations because they all work. Even Maxwell won't help you design a circuit. Transformers and inductors already have their rules condensed for you. Try not to wander. And if you can, take a nice night course in basic circuit theory. My 2c.
When I emerged with an MS into the same recession it was on to the minicomputer industry. That's all there was. There I found myself immersed in EEs (NOT educated as digital designers, not back then... they were still inventing what would be taught in later curricula) and found that 90% of my practical electronic knowledge had come not from those two good colleges but from the night course in Circuit Theory 101/102. That and my ill-funded hi-fi hobby.
Few translate E-M physics into electronics on the fly. The applications, shortcuts, tricks and abstractions have already been done (and learned by the EEs that surround you). Simply accept Ohm's Law and its variations and derivations because they all work. Even Maxwell won't help you design a circuit. Transformers and inductors already have their rules condensed for you. Try not to wander. And if you can, take a nice night course in basic circuit theory. My 2c.
The GFA-535 is not simple for me to understand but it is indeed a very simple amp and its one that nearly everyone here is familiar with.
I've said this several times in the earlier posts but it probably got lost in my word storms or I may have stated it ambiguously, so let me clarify: I do understand how a basic transistor functions. Its not difficult : voltage in excess of 0.7v turns on the transistor and causes it to pass full current. End of story (if we're talking about BJT). What I don't understand is what a circuit full of them is doing. This is no doubt related to my linear fashion of thinking. Let me give you an example of how I see these things.
Take a look at any of the Pass generation Adcoms, for the sake of this post we'll look at the GFA-555: the input signal goes in, reduces voltage and sheds any DC, then goes into a transistor. Obviously the signal gets bumped up there. There's a positive voltage at the top feeding it. That makes perfect sense. In fact, you could replace that first transistor and everything after it with one of the output boards, and my brain would say "Hey look - an amplifier!" My linear brain would be able to follow the power and the signal and the output and everything would be fine. But thats not how this works, obviously. There's a spiderweb of transistors, traces, and passives in between the first transistor of the differential pair and that output board. I can't follow whats happening. I don't know if I'm able to do that, at this point.
But back to the input board design. I see the positive rail on a given channel leading to the collectors on the differential pair. Plain as day. Before it gets there it branches off 7 times, and thats where the weirdness gets me. The first branch nearest the pair goes to a PNP. And for some reason the base of that PNP is hooked back to the positive trace that leads to the 2nd transistor in the diff pair. But the base is where signal goes in, I thought?
The second break, reading left to right, goes to a resistor. Which then joins up with three traces: one that goes to 2 diodes in series, leading.... back to the positive rail? One goes to a resistor and then ground, because of course it does (random stuff leading to ground drives me up the wall, especially when I recall that ground is actually the "negative side" of circuits. Except we also have a negative voltage rail. Arrgh), and the final trace leads into the base of a PNP, which... leads to a resistor and then back into the positive voltage rail. I don't even want to get into where the collector is going because I think I'd lose whats left of my mind, but I'll give it a try. It leads down to a 3 way junction, the bottom of the junction goes to another series pair of diodes, and either side of the junction leads to the base of its own NPN. Except one of the NPNs is accepting current from the differential pair. The other one is accepting current from, well... go back to the positive rail and keep reading.
Finally, we have two more PNPs. The base of the first one leads to the emitter of the 2nd. The base of that one leads to the collector of the first. And the collector of that 2nd transistor leads... down to another transistor which is connected... base to base with the transistor hooked to the siamese output of the differential pair. Yes I think its official, I've lost my mind. Everything is connected to everything else, and there is no clear path through anything.
While we're on the subject of the GFA-555 take a look at the output boards layout. Pick a channel. Notice one board is full of NPN and one is full of PNP. My brain looks at the NPN board, sees all of the emitters gathered on to one trace which then jumps to the next card full of PNP and follows the arrows into those transistors.
But...
Before the transistors there's a trace leading down to a diode. Before the diode there's a wire that leads out... directly to the speaker terminal. That means the shortest path to the positive speaker terminal bypasses all those transistors. So what in the 9th circle of heck (not a dark place full of fire but merely dim and uncomfortably warm) is that entire card full of PNP doing there?
And I know I'm completely wrong, and its because of these two things:
1. I can't deal with a non-linear path
2. schematics are loaded with non-linear, recursive paths
The problems with the "Dummies" books, and all of the beginner-level stuff, is that it always begins with "here's an electron - it has a negative charge" and explanations of the layers in transistors. That is completely unnecessary and I think it overcomplicates things. I didn't learn physiology by starting with chemistry. I like to get the obvious big picture stuff done and then break it down into smaller components.
I meant something I could pick up on Craigslist, already working, that I could dissect and learn from. I default to the GFA-535 because they're cheap and can be found in every town on the used market. I picked one up for under $100 in a pawn shop once. I'd hate to ruin one of mine by working on it, and apparently there are simpler amps out there, so I was hoping you or someone here could suggest another amp I could study.
I agree. I think that has done more to damage my electronics comprehension than most other things except electronics itself.
Transistors aren't quite that simple in every case. It's the relationship between the lead voltages that maters. Look up the common base circuit. Figure 3-1B.Common-emitter and common-base amplifiers
I started learning about amplifiers by studying and building single ended tube amplifiers. They don't have many parts so they can be built without too much cost and are relatively simple in operation. However, you can learn a lot about electronics including AC to DC conversion, filter design (power supply and audio), and amplifier design. If you understand how every part of the single ended amplifier works, it is a very good start.
A modern equivalent of the tube single ended amplifier would be Nelson Pass' De-Lite amplifier. There is a lot of documentation on it and there are people on DIYAudio who can provide any help needed.
I have found that hands-on in addition to learning theory is the best way to learn. That is why most science/technical courses in schools include lab work.
A modern equivalent of the tube single ended amplifier would be Nelson Pass' De-Lite amplifier. There is a lot of documentation on it and there are people on DIYAudio who can provide any help needed.
I have found that hands-on in addition to learning theory is the best way to learn. That is why most science/technical courses in schools include lab work.
As JMFahey stated, its all about physics. At the age of ten I was fascinated by magnetism. Playing with magnets, winding coils, building a primitive electro-motor based on scrap material. Later on it was radio and transmitters, then audio.
I studied physics, not electronics because I wanted to get a basic understanding instead of filling my head with myriads of ready-to-go recipes and formulas.
So if you want to plunge into physics I would always recommend "Feynmans Lectures On Physics"
The most comprehensive and entertaining textbook on physics
I studied physics, not electronics because I wanted to get a basic understanding instead of filling my head with myriads of ready-to-go recipes and formulas.
So if you want to plunge into physics I would always recommend "Feynmans Lectures On Physics"
The most comprehensive and entertaining textbook on physics
Circuit theory is important. It teaches you how to think about electronic circuits. You are at considerable disadvantage if you don't understand and know how to use basic concepts like Thevenin and Norton equivalents, Kirchhoff's laws, controlled sources, superposition, etc.
Of course, physics of electromagnetism is important too. So are other things.
Think about it, what do they teach in college electronics programs? First couple of years are mostly math, physics, and chemistry. After some background in those things comes circuit theory. Maybe feedback comes along about the same time in an introductory systems class.
With all that stuff under your belt you may be ready to start learning about amplifiers, filters, power conversion, and so on. Understanding those things is all based on understanding the basics you already should have learned.
Of course, physics of electromagnetism is important too. So are other things.
Think about it, what do they teach in college electronics programs? First couple of years are mostly math, physics, and chemistry. After some background in those things comes circuit theory. Maybe feedback comes along about the same time in an introductory systems class.
With all that stuff under your belt you may be ready to start learning about amplifiers, filters, power conversion, and so on. Understanding those things is all based on understanding the basics you already should have learned.
That's quite a generalisation. Maybe I'm the odd one out here, but I'd never heard of Adcom before you mentioned them. Perhaps it is a geographical thing.
If it is not simple for you to understand, then start on something simpler that you can understand and work your way up.
Listen to what some of the very experienced guys here have said.
There lies part of the problem. You want to breeze through the basics and get straight into understanding full circuits.
Do you understand the why of the transistor? What the depletion zone is? What a p-n junction is? Mathematically what is going on? That will help you understand why a transistor behaves the way it does.
Once you do, then move into transistor configurations. Do you understand what common base, common emitter and common collector all do and why?
Do you understand then, voltage follower and emitter follower circuits? Complementary pairs? Differential pairs?
A lot of amplifiers have similar topologies. You have a power supply section with filtering, transconductance using maybe a long tailed pair with a current source, transimpedance, output, feedback.
A circuit - any circuit - is just a collection of smaller circuits, each manipulating the voltage or current to get a desired outcome. By learning each of these little blocks, you'll be able to break a circuit down into functions.
Again, I am not familiar with Adcom products but I can only imagine you are describing where the output signal comes from. You are thinking in DC, whereas the output section there is AC. You need to understand the basics of AC - magnetism, sine waves, phase, etc. How do resistors and capacitors behave in AC versus DC? Why?
No, you are trying to run before you can walk.
If it was completely unnecessary, I don't think it would be covered as a foundation of so many courses for so many years. By all means pass through the physics once you understand it, but don't assume you 'know it all' already. Just learn with an open mind and it makes it so much easier.
I don't know what physiology course you studied but when I studied Human Biology, we started with basic chemical reactions, then basic cell structure, then cell groups. And once all the 'building blocks' were in place, the bigger picture became clear by itself. Knowing the basic chemical reactions that take place in the body made it easier to understand how the Mitochondria functioned, for example. How semi-permeable membranes functioned allowed understanding of how cell walls functioned, which helped understand how the digestive system functioned.
You are missing too many pieces of the puzzle to understand the whole picture.
Good advice, and I appreciate your story. I would definitely enjoy getting into a circuits class, but unfortunately they literally don't exist here anymore, as I found out yesterday. I checked the same schools that I'd been at just a few years ago and all the courses I'd walked past while I was taking other things simply don't exist anymore. There has to be an explanation so I believe I'm going to contact the advisor's office tomorrow and see if I can't get anymore information.
I will do that when I start studying again tomorrow. I spent the entire afternoon transcribing a schematic and noting modifications, just as an exercise. Sometimes it helps to do things from a very obtuse angle. Thank you Conrad.
Ok, a simple tube amp is now on the menu. Thanks!
As JMFahey stated, its all about physics. At the age of ten I was fascinated by magnetism. Playing with magnets, winding coils, building a primitive electro-motor based on scrap material. Later on it was radio and transmitters, then audio.
I studied physics, not electronics because I wanted to get a basic understanding instead of filling my head with myriads of ready-to-go recipes and formulas.
So if you want to plunge into physics I would always recommend "Feynmans Lectures On Physics"
The most comprehensive and entertaining textbook on physics
Yikes... Feynman isn't exactly the most approachable writer. I think you have a bit more brain than I do. But I"ll take a look at his work after I get past some of the articles recommended in this thread so far. Thanks!
If you haven't already discovered them, LT Spice comes with a crap-ton of examples. I'm trying to develop the habit of opening one and playing with it every few weeks just to work on my limited skills. Might be more fun than textbooks -- and no parts have to be ordered or get destroyed.
Yes it does, and they seem to be grouped around specific parts. I can type N2907A and get a circuit, but just typing in PNP transistor returns a few pages of non-related things. (This is just a paraphrase of an example - I can't recall exactly what I typed). Have you had any success with topical search terms instead of part-specific stuff?
I'm working on math now, coincidentally. I was always good in Algebra and I used to tutor that in college, but I walked away from geometry, and never attempted calculus. I have a bit of a mental block there as well: while I can do all the algebraic formulas (I used to thrive on quadratic forms and linears), but when it comes to translating word problems into formulas I collapse. That goes all the way back to my earliest testing - top percentiles in everything but math concepts. So now I'm trying to find out why that is, and see if I can rewire my brain to start translating the real world into formulas.
This page has helped me so much it's crazy. Great one to begin with - Full-Wave Rectifier
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