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Amateur guitar effects builder.......seeking enlightenment!

Thread starter #1
Hi - I am completely baffled by most aspects of electronic circuit design/build. I am currently up to my armpits in veroboard builds of various overdrives and modulation pedals and thinking there must be a resource or guide that I can buy that covers all the basics? I would really like to move on to a different kind of build process as I find veroboard is tricky to work with - I either cut the spacers in the wrong places or make a mess when soldering.

Recommendations appreciated and of course, I'll be making use of this resource, which looks great.

A question: I need to find an alternative transistor to LM78L05 - can anyone suggest options?

Otherwise, best wishes from Yorkshire, UK and look forward to learning many interesting things through the forum :)
 

gophert

Well-Known Member
Most Helpful Member
#2
Hi - I am completely baffled by most aspects of electronic circuit design/build. I am currently up to my armpits in veroboard builds of various overdrives and modulation pedals and thinking there must be a resource or guide that I can buy that covers all the basics? I would really like to move on to a different kind of build process as I find veroboard is tricky to work with - I either cut the spacers in the wrong places or make a mess when soldering.

Recommendations appreciated and of course, I'll be making use of this resource, which looks great.

A question: I need to find an alternative transistor to LM78L05 - can anyone suggest options?

Otherwise, best wishes from Yorkshire, UK and look forward to learning many interesting things through the forum :)
LM78L05 is a 5-volt voltage regulator, not a transistor. I am not sure why oneis needed in a guitar stomp box but I guess some effect may need a voltage reference.

Stomp boxes intentionally distort audio signals so there are few "professional" resources because most engineers want to faithfully reproduce audio without distortion.

Your best bet is searching diy effects pedals.

If you know how to design circuits and just want to make better PCBs, search Eagle CAD or DesignSpark for software to draw the pcb.

If you need help creating a copper clad board, google
Pcb toner transfer
Or
Pcb sensitized etching MG chemical
 
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#4
gophert: I have some op amps that have a max Vcc of +5V. Maybe He's using that same part?

Don't forget Kicad. It's free, which is what I like about it. :)

Here's a distortion pedal I designed a while back.

It's called "MJ's Hot Mess."

U1A is an input buffer. C1 / R1 as well as C7/R8 control the low frequency cutoff.

Tinker with these values to make a Bass pedal. ;)

U2B is the heart of the distortion pedal. I believe the configuration is called a logarithmic amplifier.
The diode pair makes all the difference here. I use a pair of 1N34As, which are germanium diodes.

U1C and U2A comprise a mixer. You can mix the clean and distorted outputs together.

If you use this circuit, don't forget to mention where you got it.

You won't find it anywhere else but electro-tech-online. ;)

Best o fluck. (This is a typo that I think I want to leave alone, just for the comedic effect.)

Uhhhh...best of luck. :)


Distortion_pedal.jpg
 
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JonSea

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#5
If you are making several copies of your circuits, you can lay out circuit boards as Gorphert suggested, but instead of etching the boards yourself, you can have 10 boards professionally made in China for around $25 all-in ($5 to make the boards, $20 for shipping). That's just for the printed circuit board to replace the veroboard. Then it would be a lot easier to assemble.
 

AnalogKid

Well-Known Member
#7
MJ, when I first looked at your circuit I assumed that the fuzz and direct path gains were independently adjustable. Now I see that the two pots are ganged, so ...

Since R3, R5, R6, R7, and VR2A and B are all equal values, you can eliminate two opamps and 1/2 of the dual pot by summing the fuzz and direct paths into the output buffer and making that stage adjustable gain.

ak
 
#8
AnalogKid: Thanks for the heads up. I thought it would provide a better control of the percentage
of clean vs distorted output. Like a pan pot.

Problem is, I don't play guitar, so it's difficult to determine what guitarists like.

When I get a chance, I'll try the mod you suggested and ask a few guitarists I know to try it out. :)
 

AnalogKid

Well-Known Member
#9
Now that you say that, I understand why the two pots are connected differently. To improve clarity, add pin numbers to the pots. Pin 3 is the terminal the wiper goes to in the full clockwise direction.

Yes, your dual pot will act as a pan between max fuzz and max clean.

ak
 

audioguru

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#10
Most people who listen to overdrive, fuzz and screamers are so deaf to high audio frequencies that they do not hear the severe distortion then they add more distortion. An acoustic guitar sounds good, even when amplified over a low distortion sound system.
 

unclejed613

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#11
Most people who listen to overdrive, fuzz and screamers are so deaf to high audio frequencies that they do not hear the severe distortion then they add more distortion. An acoustic guitar sounds good, even when amplified over a low distortion sound system.
depends on your taste in music. i happen to like the "these go to 11" version of Neil Young's "Out of the Blue" much better than i like the "unplugged version. but that's the point of effects boxes and amplifiers that go to 11, the whole system is part of the instrument, not just the guitar.
 

unclejed613

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#15
a good place to look if you are looking for unusual ideas for effects is [Analog Devices Op Amp Applications 1974] chapters 4 ,5, 6, 9, and 10. i had some unusual boxes i built as prototypes, one of them was a low distortion octave box. if you feed the same signal into both X and Y inputs of a 4-quadrant multiplier, you get an output that is an octave higher. the other prototype i built was a box that distorted the signal, not by clipping the signal, but by simulating crossover notch distortion. there was little or no distortion when playing loud, but the signal would begin getting distorted as the signal level dropped. if you sustained a note, it would gradually get fuzzier as the note decayed. it was an interesting sound.
 

unclejed613

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#16

AnalogKid

Well-Known Member
#17
Analog Device's books over the years are an outstanding body of work.

But (IMnsHO) -

No one did more to bring the amateur/young designer into the world of professional circuit design than National Semiconductor. "...well into the 1980s." ? I disagree. The Linear Applications Handbook series in general, and the specialty derivatives like the Audio Handbook, are as valuable today as ever - both to fill in what no longer is taught in schools and as a counterpoint to much of the "information" on the innergoogle.

There is a long-running thread on another forum about "bibles". We love our old TI books and the GE Transistor Manual, but NS takes the title.

ak
 
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#18
For effects schematics, have a look at this site:
http://www.effectsdatabase.com/schematics#list

Or if you want pre-planned stripboard layouts for various types:
http://tagboardeffects.blogspot.com/

I still prototype everything we design for manufacture on either stripboard or square-pad board, though I do tend to use board with a topside ground plane [A "colander" ground plane] for anything that may be sensitive to noise or ground resistance as that eliminates many problems before you start and simplifies wiring.

eg. something like these - the topside copper is show at the very bottom left of the image.
https://uk.rs-online.com/web/p/products/5184046/

That's a square-pad type, you can just bend the component leads over a row of pads to form longer connections or bend a lead to form an angled track..
 

JonSea

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Most Helpful Member
#19
There is a long-running thread on another forum about "bibles". We love our old TI books and the GE Transistor Manual, but NS takes the title.

ak
With a little searching, many of the old National books can be found online. The links seem to change as TI moves things about.

AN31: Op Amp Ckrcuit collection


AN20: An Application Guide for Op Amps


Linear Applications Handbook

These three Nation books were sold at Radio Shack (RIP) in the olden days and are favorites.
 

unclejed613

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Most Helpful Member
#20
another thing to consider if you want to design effects boxes, there have been things that were accidental, and were the basis for an effect. fuzz was "discovered" when a guitarist went into the studio to record, and blew the speaker during the session. flanging was discovered when somebody was trying to slow down the supply reel on a tape deck to make it sound like there was more than one singer on the tape, and the two signals got out of phase. the Cry-Baby Wah pedal, due to some accident with the cores for the filter's inductor added a slight amount of distortion (from asymmetric core saturation) to the sound, and made that pedal very popular. however, no two sounded exactly alike, so guitarists would try out every one a store had in stock before buying one.
 

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