The opamp circuit matches up to your circuit like this:
Rg is R219
Rf is R221
Vout is junction of R227 and R229
Opamp + input (Vin) is Base of Q201
Opamp - input is Base of Q203
If you really want to learn and understand this stuff there are a lot of books and tutorials available for free online. You need to start with the basics and work your way up.
I think a lot of people here can figure this stuff out, even if they didn't go to engineering school.
You have to study. Find a topic, get some books or online tutorials, and learn it. You can go far with just algebra and logarithms. 😉
I started building Walt Jung circuits when I was 16. I have every book he ever wrote. I have them practically memorized after 40+ years. I went to engineering school too, but what I do now I could almost do with a high school education and Jung's books. In fact Jung's books are way beyond undergrad EE curriculum, but still useful to anybody that's not afraid of algebra. I did it in high school.
If you don't start learning, you'll have to keep coming here asking basic of basics questions. I don't know about you, but I don't like to build or modify a circuit unless I understand it 100%.
Thanks Radtech and fast Eddie D. The real question is how fast? LOL
I mean I know what caps, resistors etc are but the maths and actually finding out what circuits are when in circuit can be confusing. I really love this forum because everyone helps out for free which non engineers etc seem to realise.
I'm just thankful so appreciated guys but really I want to go back to school with this and start from the bottom but with 2 kids and third on way...well you get the idea. I will have a re-read of this thread but it has fundamentally answered my question and then some. It literally bothered me for months! Thanks again and I'm sure I'll be back like I have done for years! 🙂
I mean I know what caps, resistors etc are but the maths and actually finding out what circuits are when in circuit can be confusing. I really love this forum because everyone helps out for free which non engineers etc seem to realise.
I'm just thankful so appreciated guys but really I want to go back to school with this and start from the bottom but with 2 kids and third on way...well you get the idea. I will have a re-read of this thread but it has fundamentally answered my question and then some. It literally bothered me for months! Thanks again and I'm sure I'll be back like I have done for years! 🙂
The Wikipedia article linked to has some good basics. Operational amplifier - Wikipedia
You should have those circuits, and the equations describing them, memorized. They're some of the building blocks.
You should have those circuits, and the equations describing them, memorized. They're some of the building blocks.
Yes I get that now. And it also got me thinking well is that not a discrete opamp? Can it not be used to replace the chip type? For an expert I guess the answer is yes. I mean cannot it be copied and made into an opamp.
Random question but cannot the preamp/discrete opamp not be improved? At a glance for an expert could one just glance at it and figure what components can be replaced. I'm not just talking about upgrading caps etc because that was the plan in the first place hence the thread. I'm referring to the schematic for the Teac
Random question but cannot the preamp/discrete opamp not be improved? At a glance for an expert could one just glance at it and figure what components can be replaced. I'm not just talking about upgrading caps etc because that was the plan in the first place hence the thread. I'm referring to the schematic for the Teac
These courses are free:
Electric Circuit Analysis - Wikiversity
Lecture Notes | Circuits and Electronics | Electrical Engineering and Computer Science | MIT OpenCourseWare
Circuit analysis | Electrical engineering | Science |
Khan Academy
And a good free book.
http://www.csun.edu/~acm31201/Old C... of Electronics - P[1]. Horowitz, W. Hill.pdf
Thanks for the links. The lecture videos is most appealing. Thanks for taking the time to send that!
Yes, your circuit is a discrete op amp. And almost all modern power amplifiers employing conventional topology are discrete op amps.
Understanding op amp circuit configurations means you understand a lot of discrete circuits too.
Sometimes minor improvements can be made. You already know about replacing caps. Sometimes replacing certain resistors with low noise units can make a modest improvement. But often there isn't much that can be done.
That's why I roll my own.
FWIW I have been designing and making MI and PA equipment since 1969, and am an early user of Op Amps ... which way back then were VERY limited: choice was between 741 , 741 and 741 😉
Not only I had limited choices, lots or real PRO equipment manufacturers /such as HH, Oberheim and even Neve or Studiomaster) used them because ... there was nothing else!!!
In spite of that, lots of cool things could be made, but in some critical places they simply were not good enough ... and that´s an understatement.
I resented high hiss level when used as balanced microphone preamps, so had to cook my own , discrete one.
Very simple, just a PNP differential pair and a single NPN transistor loaded with 4k7 , fed from +/-15V and with modest 10X (20dB) gain ... which was all that was needed, after that signal levels were more reasonable and hiss was not that big a problem.
Used them for ages, until RC4558 appeared, which was designed specifically for Audio, had lower hiss and, of course, used PNP transistors 🙂
Only audio specific Op Amp before it was oddball RC4739 , but it was not widely available, had oddball pinout, and required external compensation, so it was never very popular ..... plus .... "home cooking always tastes better" 😉
Not only I had limited choices, lots or real PRO equipment manufacturers /such as HH, Oberheim and even Neve or Studiomaster) used them because ... there was nothing else!!!
In spite of that, lots of cool things could be made, but in some critical places they simply were not good enough ... and that´s an understatement.
I resented high hiss level when used as balanced microphone preamps, so had to cook my own , discrete one.
Very simple, just a PNP differential pair and a single NPN transistor loaded with 4k7 , fed from +/-15V and with modest 10X (20dB) gain ... which was all that was needed, after that signal levels were more reasonable and hiss was not that big a problem.
Used them for ages, until RC4558 appeared, which was designed specifically for Audio, had lower hiss and, of course, used PNP transistors 🙂
Only audio specific Op Amp before it was oddball RC4739 , but it was not widely available, had oddball pinout, and required external compensation, so it was never very popular ..... plus .... "home cooking always tastes better" 😉
Its is starting to make sense now. I guess I really need to start at the bottom of how transistors actually amplify the sound like good old tubes used too before jumping 10 steps a head.
You never know I could end up inventing a new amplifier!!!?!
Thanks for input! and past experience!
You never know I could end up inventing a new amplifier!!!?!
Thanks for input! and past experience!
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