Pedal Design & Education

[Dylfish]

Hey Guys,

I'm wondering since I'm wanting to design my own pedals eventually what level of electronics should I be reading? I grabbed a copy of the book of the art of electronics but reading through parts I'm not sure whats useful and whats wasted.

I'm assuming I dont need to get to the standards of an EE, but what do you guys find useful when designing?

[MaxPower]

I recommend Electronic Principles by Malvino. Doesn't have to be the latest edition. Slightly older editions can be had for less than $10 on Amazon. Covers a lot of the basics with transistors, jfets, mosfets, capacitors, and op amps (amongst various other components). The book is worth it for the op amp chapters alone imo. The one shortcoming as far as guitar pedals go is the transistor section. It (the edition I have anyway) primarily covers the voltage divider bias (common emitter?) configuration and skims over some of the other transistor biasing methods (while omitting others).

If you can find a copy of Transistor Circuit Approximations (also by Malvino) I highly recommend that as well. I have a second edition and this does cover the various transistor biasing methods. Don't be fooled by the title, it also gives you the formulas for precise calculations. It even has a chapter dedicated to the h parameters if you want to drive yourself insane. Covers capacitors (frequency characteristics) and jfets a little bit as well.
 

[Dylfish]

Cool,

What type of theories / subjects should I tackle?

[dwmorrin]

Congrats on getting "The Art of Electronics."
The essentials are:
Ch. 1 Foundations - You should know everything here.  It's mostly the same stuff you get out of any basic electronics book.  Refer to it for the elementary stuff.  If you don't understand something later on, you may need to re-read a paragraph or to here first.

Ch. 2 Transistors - Try to master this chapter.  Some hints: they introduce transistor current sources (2.06) before common emitter amplifiers (2.07).  You may be tempted to skip or skim 2.06 because you may not be interested in current sources just yet, but you probably won't understand 2.07 if you do (speaking from experience!).
Don't sweat the Ebers-Moll model (2.10).  Skim that section.  Then it's amps again, until you get to current mirrors (2.14) - not essential on your first pass - more good amp stuff follows... 2.19 is probably a skim/skip on the first pass as well.
I highly recommend picking up "Solid-State Servicing" by William Sloot for an even better tutorial on understanding and designing with BJTs.  It's also more focused on practical audio amps than "Art of" is.

Ch. 3 FETs - Another must read.  This chapter is fairly easy to just plow through - don't stop at every equation... the important stuff is just to get your head around the common types of FETs, how they are different (JFETs are usually "depletion mode", MOSFETs are usually "enhancement mode", but not always, etc.).  The logic and switching stuff can be ignored if you're not interested in those circuits yet.

Ch. 4 Feedback and Op Amps - This chapter is a mix of essential and non-essential stuff.  4.01-4.06 should be understood thoroughly.  Then there's quite a bit that can be skimmed on first pass.  4.21 introduces single supply ac amps, which is how to get to a single +9 power, instead of a bipolar +/-15 supply (the "standard" op amp supply scheme).  You'll want to learn how to take a bipolar schematic and convert it to single supply.  4.23, 4.24 - Comparators and Schmitt triggers are not essential on the first pass, but don't skip these the second time around.  You'll need them for many interesting and utilitarian circuits (lighting LED indicators comes to mind).

The feedback part of the chapter starts at 4.25.  Read 4.25, .26, and .27.  Skim the rest of the chapter.

Ch. 5 Active Filters and Oscillators - Non essential until these things interest you.

Ch. 6 Voltage Regulator and Power Circuits - 3 terminal regulators are the primary thing a DIY pedal maker should know.  Mastering the unregulated supply (6.11-13) is probably next in line, and then the rest you can pick out as needed.

Ch. 7 Precision and Noise - skip precision, but read through noise.

Then it goes digital for the majority of the rest of the book.  Read on only if and when you're interested in digital circuits.

At the end of the book, there is some good info in the appendixes.  There's a scope tutorial, math review, and a good guide to drawing schematics.  Don't miss those.

[Dylfish]

Some hints: they introduce transistor current sources (2.06) before common emitter amplifiers (2.07).  You may be tempted to skip or skim 2.06 because you may not be interested in current sources just yet, but you probably won't understand 2.07 if you do (speaking from experience!).

Thanks, I was tempted but i'll put in a concerted effort

This might sound stupid but is it more important to have everything 100% down pat or is it better to understand what it's doing rather than just knowing how to do it?

[dwmorrin]

This might sound stupid but is it more important to have everything 100% down pat or is it better to understand what it's doing rather than just knowing how to do it?

It's a good question, and I'd say knowing "what it's doing" in an intuitive way is much more useful 95% of the time than knowing how to design a new circuit from scratch.  I think that's what you mean?

Another way to look at it: it takes many "passes" through these electronics textbooks to develop real understanding.  Re-read sections many times, and collect many books, even if they seem redundant.  The redundancy will speed up your learning.
You have to read stuff you don't understand in order to (hopefully) inspire you to re-read the basics again.  Look at it that way, instead of being discouraged if you don't understand something.

It's far more important to have the elementary theory and formulas "100% down pat" than any particular circuit.
The topics to master first are: Ohm's law, Kirchoff's circuit laws, and voltage division.  If you're shaky on any of those, trying to follow a tutorial on amplifier design will be difficult to impossible.
All of those topics only require basic algebra.  I would highly recommend sitting at your bench with a power supply (9V battery is fine) and some resistors and a multimeter to verify what you're learning.

[Gus]

The real answer is to go to school and/or read books and build and test and measure and repair circuits for a good number of years

How deep do you want to get, physics of the devices and analysis of circuits or cut and paste?

There is a lot of things to know to do a good design.

Good things to start with are Ohms law, Power math, being able to solve resistor networks for current and voltages
Math skills help a lot. 
RC time constant
Then AC and RCL networks

"The Art of Electronics" is a good overview but it is not the only book to read.  See if you can find any books by http://en.wikipedia.org/wiki/Forrest_Mims

The web makes thing easer as a kid I would go the library to read the latest electronics magazines and the back issues (Scientific American had a cool thing called the amateur scientist) and any books I could find about electronics and started building circuits and other things like DC motors.  When I started working I bought books about electronics and built all kinds of circuits.  School helped a lot. 

Mechanic design matters, layout design matters, art design matters, marketing knowledge matters, Understanding your liability when selling things matter. 

[PRR]

Congrats on getting "The Art of Electronics."
The essentials are:
Ch. 1 Foundations - You should know everything here.  It's mostly the same stuff you get out of any basic electronics book.  Refer to it for the elementary stuff.  If you don't understand something later on, you may need to re-read a paragraph or to here first.

I would order the lessons like this:

Ch. 1 Foundations - You should know everything here.
Ch. 1 Foundations - You should know everything here.
Ch. 1 Foundations - You should know everything here.
Ch. 1 Foundations - You should know everything here.

In my experience (my own, and helping others), the main hangup isn't "transistors", it's Basic Electricity. Battery and resistors.

Students rush ahead to the sexy stuff, transistors, but then don't have a clue what happens in the total circuit so the transistor action remains mysterious.

I'd run a school like a military boot-camp. Where you do about a billion Ohms Law pushups before you ever see a weapon.

[R.G.]

Let me add to that.

It's entirely possible - well, OK, it was, before analog design became completely passe in the industry, and digital is the main thrust - to have a successful career as an EE with little more than an understanding of Rs, Ls, and Cs, their basic combinations, and Ohm's Law. I KNEW EEs that were limited to that, but they did it very well indeed.

Once you know all the possible permutations of Ohm's law, what power is, and some of the generalizations of Ohm's law to AC and impedances, you're ahead of probably 99% of the people registered on this (or any other, likely) forum, and vastly more than that of the unregistered.

This is not because people are so lazy and stupid that they can't or won't learn it (necessarily - there are exceptions) but because for all its apparent simplicity, Ohm's Law is subtle and pervasive in its application.

Once you have Ohm's Law down, the rest gets much easier. But getting to there may take a very long time indeed.

Ohm's Law resembles what I once heard about guitars - the guitar is the easiest of all instruments to play poorly, but one of the hardest to play well.

[teemuk]

Students rush ahead to the sexy stuff, transistors, but then don't have a clue what happens in the total circuit so the transistor action remains mysterious.

It's the weird attitude that assumes one can just straight cut to the interesting stuff with right kind of reference, forgetting all the tideous, time-consuming and hard stuff.

I'm pretty sure no-one in his sane mind would loose his face asking a question like "I know nothing about car motors, which book can I read to learn how to tune F1 race car engines?" but a for some reason "I know nothing about electronics, which book can I read to learn how to build amps/effects?" seems to make perfect sense.

Sigh.

[tubegeek]

Don't overlook several online resources:

GEOFEX (RG's site, www.geofex.com) which comes at most things from a pedal-effects perspective but which contains a tremendous amount of general-purpose knowledge.

ESP (Elliott Sound Products, sound.westhost.com) which has numerous audio-oriented projects and a broad array of general-purpose audio electronics articles.

Wikipedia (wikipedia.org) for looking up a factoid here and a factoid there.

Manufacturer's data sheets for every part you use. (Google the part number, follow the hits that take you to manufacturers' web sites.)

[R.G.]

Students rush ahead to the sexy stuff, transistors, but then don't have a clue what happens in the total circuit so the transistor action remains mysterious.

It's the weird attitude that assumes one can just straight cut to the interesting stuff with right kind of reference, forgetting all the tideous, time-consuming and hard stuff.

I'm pretty sure no-one in his sane mind would loose his face asking a question like "I know nothing about car motors, which book can I read to learn how to tune F1 race car engines?" but a for some reason "I know nothing about electronics, which book can I read to learn how to build amps/effects?" seems to make perfect sense.

It's an inbuilt feature of human psychology. See http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

People who know little also don't know how little they know, so they underestimate the time and effort needed to get competent, and overestimate how competent they are or soon can be. Mid level learners know more about how little they know, so are better judges of how competent they are and how much more is needed to become an expert. Experts know a lot, and also know a lot about what they don't know, so experts actually tend to UNDER-estimate their competence.  Well, some of them, anyway.

It's human.

[solderburn]

Are there any internet articles about circuit construction? Basically for explaining how each part effects the circuit?(Distortion & Fuzz)

I would love to get the Art Of Electronics but i don't have the money.

[dwmorrin]

Are there any internet articles about circuit construction? Basically for explaining how each part effects the circuit?(Distortion & Fuzz)

GEOFEX (RG's site, www.geofex.com) which comes at most things from a pedal-effects perspective but which contains a tremendous amount of general-purpose knowledge.

ESP (Elliott Sound Products, sound.westhost.com) which has numerous audio-oriented projects and a broad array of general-purpose audio electronics articles.

Wikipedia (wikipedia.org) for looking up a factoid here and a factoid there.

To add to tubegeek's list:
http://www.beavisaudio.com/  Look under the "tech" section.
http://www.kitrae.net/music/big_muff_guts.html
http://moosapotamus.net/stompboxology.html
http://www.electrosmash.com/

There's probably dozens more out there...

[R.G.]

Are there any internet articles about circuit construction? Basically for explaining how each part effects the circuit?(Distortion & Fuzz)

That's a common misconception - that one can learn how a resistor or capacitor affects the circuit. I've seen several comments like that here.

A part doesn't affect the circuit. Rather, the circuit is the thing that matters, and that is what changes the sound eventually. For example: a single resistor and single capacitor filter. It is possible to get the same relative filtering with an infinite number of values for resistor and capacitor. Only the product of R*C changes the frequency change point of the filter. But the overall impedance of the filter changes, from very low with low-R/high-C to high-R/low-C combinations with the same R-C product. So a circuit which has to drive a low-R/high-C filter may have to spend a lot of power to do it, and itself need a low internal impedance. If the filter drives a low impedance - like an electric motor    then it may need to be low impedance.

To more directly answer your question, yes, there are probably thousands or tens of thousands of internet articles on how circuits work. But you need to find a string of them with a consistent flow and focus.

And you also asked about construction, then how each part affects the circuit. Construction is in general removed from the electrical operation of the circuit. There are many places with construction techniques, but this is different from design techniques, which is more like how the parts or circuit affect the operations.

Again, the right way to learn this stuff is to start with basics. Learn what resistance is, what reactances (Ls and Cs) are, and how they interact. Learn Ohm's law. Learn simple circuits. Without those under your belt, learning about parts in distortion or fuzz circuits is like polishing... um, deposits of scat. The surface might be shiny, but the shine is thin and what's underneath doesn't have a whole lot of value.

I should note that I asked that same question when I was in my teens. The answer I came up with was to spend four years in a college to get the basics down, then about five years of practice with experienced circuit designers keeping me from the most fatal of my mistakes. And I did that because I wanted to learn how to design musical equipment. It was a long, meandering path.

[solderburn]

Reviewing my comment i have realized that i have improperly worded it, What i meant was I any one knew of a article that took a circuit, and explained what each part did, thus giving me a idea how it worked. Just to help me learn how Individual parts work in circuit. Thus making it easier to understand examples that tutorials give. (I sometimes get extremely confused when reading them) Realizing you have to learn to crawl before you can run is very important, I am coming to know.

Geofex has stuff that i haven't read(that i am reading now!)Rod Elliott's website has a LOT of information that i most certainly will be reading!

Sorry if i upset any one with my stupid questions.

[PRR]

> my stupid questions

Not stupid. Ignorant. And ignorance can be cured.

And get-over the hammering we gave you. Nobody is born knowing this stuff. Men much smarter than any of us struggled to develop electricity and electronics. Even the "self-evident" Ohms Law was widely rejected for its first decade. From tubes to good amplifiers was a decade of many very-smart men trying to wrap their heads around new concepts. It took a decade for transistor amplifiers to get good, and a LOT of very smart men and much money wrestled with that one.