My First Schematic Attempt

[boyersdad]

Well, sitting at the bar where I do sound for a living, waiting for a particularly slow band to set up, I got the idea for this distortion pedal. A friend of mine really wants a distortion box that has two seperate distortion stages, and two seperate stomps. I wrote this up on paper, and transfered it to Eagle. I still don't know which one is messier, lol.

It use three OPA's. The first is a buffer and active tone control. The second is the first, and heaviest distortion stage. D1, D2, D3, D6 and D7 are all 1N914, and D5, D6, and D8 are 1N34 or other geranium.

All this is just off the top of my head, and will probably need A LOT of value tweeks etc.

Obviously there are things missing in the schematic. Bypass switch, power/gnd to the opamps, etc. I just tried to get the basic ideas in there for now. This is my first attempt with Eagle. I'm just starting to get the hang of it.

Any suggestions, comments, and questions welcome!




Sorry about the quality and size of image. Darn photobucket.

[aron]

You can use the gallery to upload a schematic. See reply #9:

http://www.diystompboxes.com/smfforum/index.php?topic=21.0

I can't read the cap values but if that's a 22uF or 2.2uF, even then it looks too large unless you want a very bloated, fuzzy sound.
I don't know about the cascading op amps. He might get more variety with 2 separate overdrive paths instead of cascaded.

You might want to ground the input of the unused stage.

Good luck!

[The Tone God]

Photobucket uses different methods to restrict image size. One way by the actual physical image size which I guess you have set. This shrinks the image on transfer. If adjust your profile to restrict by file size then you won't have the restriction unless your image is more then what you specified.

Andrew

[Phorhas]

Just a small thing - you have the 1M pot in the input stage bypassed, so there will be no amplification there IMO. Cool first schematic, BTW


Dan

[oskar]

D9 polarity!? 
Nice drawing!

[oskar]

I think c9 should rather be hooked up to the inverting input...     

[Elektrojänis]

Just a small thing - you have the 1M pot in the input stage bypassed, so there will be no amplification there IMO. Cool first schematic, BTW

That, and then it needs a path to ground or VR via suitable sized resistor (and possibly a cap too, especially if it goes to ground) to have any gain. The feedback network is really a voltage divider for the feedback signal. If nothing from the feedback path goes to ground, then everything goes to inverting input, and the gain will be 1.

[Elektrojänis]

Another thing... Input impedance is only 10kohms (set by R6). That's a bit low for use with guitar. It might sound fine, but if it sounds too dark/muddy, you might try making that resistor bigger.

[boyersdad]

Another thing... Input impedance is only 10kohms (set by R6). That's a bit low for use with guitar. It might sound fine, but if it sounds too dark/muddy, you might try making that resistor bigger.

Woops. That was supposed to be 100k!

Now that I'm looking again I'm noticing a few errors myself, so I'll revise and repost, this time in the gallery so you can actually read the thing!

Thanks for the input everyone! 

[gaussmarkov]

you may want to update your jacks library.  i made a mistake in labeling that appears in your schem.