Amplifier theory

[icke2433]

Hey there all, I'm attempting to teach myself some amplifier theory so I can begin analyzing guitar pedals to see exactly how the tick. I found an old physics lab online that has helped me a ton but unfortunately I don't know how to check and see if I'm getting the correct answers. Can anyone help me out? Or send me somewhere where I can ask questions? Thanks!

 

[icke2433]

Also, I did these calculations assuming there is no ac signal. How would I evaluate it for an ac input? (This is designed for a two volt ac input I believe) are the capacitors on the right hand side meant to correct for ripple?

 

[seamonkey]

LTspice is free, and a great tool to learn. Spice is general is good to learn.

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Draw the schematic in spice then run it. Put scopes on it. Run different signals through it.
There are all kinds for free spice models for amplifiers and effects available on the net.
It's a modern electronic designers tool.

 

[agedhorse]

Ce is for increasing voltage gain by decreasing local AC feedback
CB is for reducing ripple or supply impedance (also reduces noise coupled into the supply by the amplifier itself)
Cout blocks the DC from the output, since the signal (ideally) operates (centers) at 1/2 of the +15 volt DC rail voltage.

Keep learning this way, simulation tools are helpful adjuncts to learning, but I have seen folks who think they can design by using a simulation program but it's painfully obvious that they have no idea what they are doing and the results show it (both in performance and failures).

 

[beans-on-toast]

I don't know if there is an easy path to learning these things. It's a long process and requires some dedicated work. You have to sweat through the details.

One approach is to find an introductory engineering text book on transistor design or electronics in general and work through it. There are free books listed here: Technical books online These books are mostly tube related but there are some transistor texts.

There are ebooks available, perhaps start with this one: Invalid Link Removed. As you'll see, there are two parts to an analysis of a circuit, DC is usually done first, then AC. Assumptions are usually made to simplify the analysis. There is no substitute for building a circuit and measuring what is going on.

If you search, you will find some books that examine stomp box theory. There is some good references on stomp box forums such as diystompboxes.com.

 

[icke2433]

Thank you guys! I'm downloading spice right now. Darkhorse that clears things up and I'll definitely look at the bjt transistor theory pdf. Much appreciated.

 

[Kirk Bryant]

Darkhorse where's a dark horse ...I thought I tah a puddy cat.

 

[Passinwind]

Thank you guys! I'm downloading spice right now.

Which flavor? The LTspice Yahoo group has a great library of tube amp models and lots of other cool analog audio stuff in the Files section. As Agedhorse says, it helps to go in with hands on practical knowledge before you get too wound up in modeling, but I have managed to build several pretty decent widgets straight from LTspice to circuit board layout software in the last few years. It's great for helping to answer what-if questions, but as always, asking the right questions is the key.

 

[Woodstockz]

I don't know if there is an easy path to learning these things. It's a long process and requires some dedicated work. You have to sweat through the details.

One approach is to find an introductory engineering text book on transistor design or electronics in general and work through it. There are free books listed here: Technical books online These books are mostly tube related but there are some transistor texts.

....

"The Art of Electronics by Paul Horowitz" is your huckleberry.


+1 on the dedication and sweat.

 

[cfsporn]

What physics lecture is this? I've been looking for something along these lines for a while.

 

[seamonkey]

A cool Reddit list!
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Start from "go". Right at the top, Radio Electronics Mag 1921 - 1927

 

[cfsporn]

What are some good "dead tree" type books? I have this one and it has proven to be very useful. I also have a 1968 copy of the RCA receiving tube handbook, but that's all.

I guess could look at my school's book requirements for the classes I'll be taking in the coming years, but I would like to hear any and all recommendations.

Sorry for the thread hyjack.

 

[Woodstockz]

What are some good "dead tree" type books? I have this one and it has proven to be very useful. I also have a 1968 copy of the RCA receiving tube handbook, but that's all.

I guess could look at my school's book requirements for the classes I'll be taking in the coming years, but I would like to hear any and all recommendations.

Sorry for the thread hyjack.

As I mentioned before....

This is what you need.

Take a look at the reviews.

 

[beans-on-toast]

As I mentioned before.... This is what you need. Take a look at the reviews.

Good book.

There's a new third edition out this year, your pointer is to the previous edition.

 

[Woodstockz]

Good book.

There's a new third edition out this year, your pointer is to the previous edition.

Ha, ha. I've had mine for a long time - I didn't even know there was a second edition. I guess I will have to upgrade my dead tree ware to V3.0.

 

[beans-on-toast]

Here's a link to the third edition: The Art of Electronics: Paul Horowitz, 3rd edition. Textbooks are expensive.

 

[cfsporn]

Good book.

There's a new third edition out this year, your pointer is to the previous edition.

If beans-on-toast and Bob Lee both say it's good, then that's enough of an endorsement for me!

What is new with the 3rd edition? While the laws of physics haven't changed much in 26 years, technology has advanced exponentially (Moore or less ) so I am kind of at a loss. Also, any verdict on the Student Manual?

 

[beans-on-toast]

Don't forget Woodstockz, he initially suggested it.

Old textbooks are still very good. The RCA Radiotron Designer's Handbook, 4th edition by Langford-Smith which was published in 1953 is still the tube design standard. It's still available as a reprint today.

To quote the publisher of The Art of Electronics.....

At long last, here is the thoroughly revised and updated third edition of the hugely successful The Art of Electronics. It is widely accepted as the best single authoritative book on electronic circuit design. In addition to new or enhanced coverage of many topics, the third edition includes 90 oscilloscope screenshots illustrating the behavior of working circuits, dozens of graphs giving highly useful measured data of the sort that is often buried or omitted in datasheets but which you need when designing circuits, and 80 tables (listing some 1650 active components), enabling intelligent choice of circuit components by listing essential characteristics (both specified and measured) of available parts. The new Art of Electronics retains the feeling of informality and easy access that helped make the earlier editions so successful and popular. It is an indispensable reference and the gold standard for anyone, student or researcher, professional or amateur, who works with electronic circuits.

 

[abarson]

I learned using Malvino's "Electronic Principles", which was a textbook/workbook pair. Of course that was a few decades ago, but I thought it was well presented and covered common circuits and different classes of amplifiers very well.
Spice is nice, but I don't think there's anything like getting a breadboard and building circuits yourself. Not only do you gain visual confirmation of your work, but you get the absolutely necessary practice of troubleshooting it when it doesn't work. Breadboarding gives you an appreciation of the benefits of layout in your design as well.
Enjoy the learning process, and don't be afraid to ask lots of questions.

 

[cfsporn]

Don't forget Woodstockz, he initially suggested it.

Old textbooks are still very good. The RCA Radiotron Designer's Handbook, 4th edition by Langford-Smith which was published in 1953 is still the tube design standard. It's still available as a reprint today.

To quote the publisher of The Art of Electronics.....

At long last, here is the thoroughly revised and updated third edition of the hugely successful The Art of Electronics. It is widely accepted as the best single authoritative book on electronic circuit design. In addition to new or enhanced coverage of many topics, the third edition includes 90 oscilloscope screenshots illustrating the behavior of working circuits, dozens of graphs giving highly useful measured data of the sort that is often buried or omitted in datasheets but which you need when designing circuits, and 80 tables (listing some 1650 active components), enabling intelligent choice of circuit components by listing essential characteristics (both specified and measured) of available parts. The new Art of Electronics retains the feeling of informality and easy access that helped make the earlier editions so successful and popular. It is an indispensable reference and the gold standard for anyone, student or researcher, professional or amateur, who works with electronic circuits.

My bad.

Thank you @Woodstockz !

I actually prefer older textbooks. I find them easier to read. Unfortunately, most of them are only available in PDF formats, and I am unable to stay focused on the thing I am reading when I am reading it on the computer. One moment I am focused and in the zone, then one "CMD+T" later I have wasted an hour of my life.