My New Project.......and My New Questions

[GuitarLord5000]

Ok.  I've decided to try my hand at a new project without the benefit of a step by step pictorial.  Lord help me!  The box I'm intending to try is a Big Daddy distortion.  The schem is here:
http://runoffgroove.com/grace.html  Thank you runoffgroove!

I looked over the schem, then went to the Shack to find parts.  I came out of there fairly disappointed.  There were no 4M7 resistors there, no .0068 caps there, and the only 2u2 cap they had there were the non polarized axial type.

I looked through my stash of scavenged parts, and think I've got the right resistor.  The color code is 1. yellow 2. violet 3. gold,  is this the right one?

As for the 2u2 cap, is this one usable, or did I just waste my money?

The .0068 cap is a little more difficult.  Looking throught my spare parts, I found a .0022 film cap, a .001 ceramic cap, and a .01 film cap.  Will any of these work, or will I have to find the .0068 cap lest my circuit fry or (even worse) sound terrible?

Thanx in advance for the replies.  And sorry for the multitude of newbie questions.

[GuitarLord5000]

OK, I've looked around here and other sites and have answered some of my own questions.  After all, this site is meant to be a helpful crutch and not an entire electronics lesson right?
    The answer to my first query about the resistors......NO YOU DO NOT HAVE THE CORRECT RESISTOR!  Idiot!  However, for you beginners out there who havent quite picked up on all the ins and outs of resistor color codes, I recommend you check out this site:
http://www.dannyg.com/examples/res2/resistor.htm
It has a very helpful color code calculator.  I saved this page as a Web Archive on my harddrive.  
    The answer to my second query.  Can I use a non polarized capacitor for that polarized one on the schematic?  Absolutely.  I found that one in the DIY FAQ on this very site.  However, after searching through my scavenged parts....again....I realized that I already have a 2u2 polarized cap.  :oops:
    However, about the .0068 cap, I'm still not sure about that.

[aron]

You probably need the .0068uF cap, the .002uF will probably cut off too much lows.

You can try it though if you use a socket.

[brett]

The 4M7 resistor can just as easily be a 1M, 2.2M or a 3.3M.  As long as it's over 1megohm you'll be right.
The 0.0068uF cap is a coupling cap that rolls off some bass.  The way I see it, it wouldn't matter much if you used a 0.01uF cap there.  They should be more readily available.  It'll just let a very little lit more bass through (barely noticeable, and might be a good thing).

good luck

[Ansil]

use a .01 it is close to the .0068 personally since you are using a buffer in front of the lm386 i wouldnt' use anything less than a .1uf  but it depends on how much bass you want in the signal personally i am the only gutiar player for the most part so i look to feel out the spectrum as much as i can

[GuitarLord5000]

Thanx for the replies!  

What i'll do is socket it and try both the .01 and .1 caps.
I'll use a 2.2M resistor in place of the 4M7.  Thanx!

Just ONE more question.  On closer inspection, I realized that the resistor that i originally thought was a 15k is actually a 75k.  Would a 10k resistor work in its place?  Its the one that goes from the +9v to the drain on the JFET.

[Travis]

Do it the true DIY way.  Us a 10k in series with two 10k's in parallel.
         
Well, that looked terrible.  Just the equation, then.

10k + 10k/2=15k

cool?

Make it LOOK like DIY

[spongebob]

You could also stick a small trimpot (20-50k) in place of the 15k resistor and tune it until the sound suits your taste  :wink:

[GuitarLord5000]

OK Travis, when using two resistors in parallel, only the second one is halved?

And Spongebob, what exactly is the 15k resistor doing in that particular spot that would alter the sound?  I was under the impression that it just set the flow of the electrical current or something.  Right now I'm just copycatting schems, but am very curious about what the components I'm wiring together actually DO.

Sorry, I'm extremely new to this.  Hell, it wasnt until a few hours ago that I learned that a JFET was just another type of transistor!

[spongebob]

Guitarlord, have a look at the Odie (also from runoffgroove), it uses trimpot instead of fixed resistors to bias the JFETs:
http://www.runoffgroove.com/odie.html

Adjust drain trimpots for approx 4.5V

A very good read on FETs is an article from the Nuts & Volts magazine
(link), I think it was posted here some time ago. It's Part 1 of a series dealing with Field-Effect Transistors, you might try the others too:

Part 2
Part 3
Part 4

[smoguzbenjamin]

No, mate. A resistor in parralel with another resistor is calculated as follows:

1/Rtotal = 1/R1 + 1/R2

and so on, depending on how many resistors you use. So, 1/10 + 1/10 is obviously 2/10. Invert that to get 5.

It's the other way with capacitors, parallel caps will add up, series caps are culculated in the same way as I described for resistors in parallel

[GuitarLord5000]

Thanx for the replies!  Heres my current status:

I couldn't find any 2.2M resistors from radio shack, so I wired 3 - 1M resistors in series to give me the 3M that will hopefully work for this circuit.

Radio Shack doesn't have any trimmers in the values specified, but I found a 15k resistor, so I'm good there.

My circuit looks like a solder monster!!!

The only thing left right now is off board wiring, which I'm having a little trouble with.  I know how to wire the input jack and 9v power supply.  I imagine that drive lug 1 goes to ground?  I dont have any 1k linear pots, so I'll be using a 5k for the drive control for testing purposes.  Where do I connect volume lugs 1 and 2?  There again, I imagine lug 1 goes to ground?  And based on the schem, I think that the output jack would be connected after the volume pot.  Is this right?

[GuitarLord5000]

AAAAGGGGGGGHHHHH!  I connected drive lug 1 to ground, volume lug 1 to ground, and volume lug 2 to the output.  When I plugged it in and tweaked the knobs a bit, I was able to get a distortion sound.  However, the sound of the distortion was outrageously overpowered by a high pitched squealing noise that was horrible!  I tweaked the knobs some more and the squeling went away, but the sound that was left was a very thin synth sout of noise.  I tweaked the knobs some more and got no sound at all.  Any ideas?  Did I hook the off-board components wrong, or does it sound more like a circuit problem?

[Peter Snowberg]

Yikes!

The little "N.C." on the schematic means "no connection". Try unhooking that and see what happens.

If there isn't a ground symbol on the schemaic, you're taking your chances by adding a ground there.

Good luck!

Take care,
-Peter

[GuitarLord5000]

Hey, Thanx Peter!  That was the ticket!  This is only my seond pedal build, so I'm not that good at reading the ins and outs of a schematic.  However, practice makes perfect.  I've got ONE last question.  The circuit I built sounds good and has wonderful picking dynamics, but the amount of gain is a little low for my taste.  I used a 10k resistor in place of the 15k.  Would an increase in that resistor value give me more gain?

And by the way, thanx to everyone for putting up with my multitude of questions.  And cudos to you spongebob for the reading material.  A little of it is somewhat out of my league right now, but I've saved it on my harddrive and intend to check it out thoroughly.

[smoguzbenjamin]

Lower source emitter = higher gain, if I'm not mistaken.

[GuitarLord5000]

Does that mean that my Radio Shack JFET sucks?  Or are you trying to tell me something that my newb brain cant figure out?

Oh, and my Radio Shack JFET does suck.  Thank you DIY faq!

[smoguzbenjamin]

Just think that more current can flow through the FET if the resistor is smaller That makes it simple.