fun octave circuit

[Steben]

Do you mean to say that it give a low impedance?
Usually an emitter follower has a high input imp and a low imp out that works to buffer a tone control.

john

high at the end of the bazz fuss 
Here you go:

[mac]

I have to try the emiter follower in my Germanium Bazz Fuss. Thanks for the tip.

mac

[culturejam]

I was goofing around with this tonight. It's a nice little circuit and ripe for experimentation.

Observation: I replaced the 10k feedback resistor with a B10K pot just to see what would happen, and to my delight, the pot acts as a nice way to control some of the octave. At 10K, it's the normal, octave-city sound, and at 0k, it sounds like a low-gainish fuzz. And obviously there is some play room in the middle. Fun!

Observation: I cannot get unity gain. Perhaps a buffer at the end is in order. I also tried a MosFET booster in front of and after the circuit, and it's a little better, but the tone is colored too much.

Question: I tried several different diodes, but the only one that sounds totally good is the 1N4001. (I also used a 5.1v Zener, which gave interesting results and warrants further investigation). Even a 1N4148 didn't sound as good, and it has the same forward voltage as the 4001. Why is this?

Question: What is the purpose of the 100K resistor to ground after the output cap? I've tried the circuit with and without this resistor, and I'll be damned if I can hear a difference.

Thanks!

[snap]

the 100k is an anti-pop pulldown resistor!

[rousejeremy]

ok here is a much improved version!
the darlington can be what ever (home made even)
the octave is now way more pronounced.
thanks for mentioning the closeness  to the bazz fuss, it gave some good inspiration.

I just built this on perfboard and the transistor exploded, parts of it hitting me in the head.
Next time I'm going to wear a helmet.

[rousejeremy]

Here's a Vero Layout of the Octave/intermodulator with an Emmiter Follower, as suggested earlier in the post. It's still a little quiet, so I put an LPB boost behind it on the breadboard with good results.



Note the trace cuts underneath the diode.

[doug deeper]

fyi!
this took some twists and turns and ended up as this:
http://www.youtube.com/watch?v=5EF2-mrqv58

[rousejeremy]

Wow, that's some crazy twists and turns. Awesome pedal too btw!

[doug deeper]

heres the peace gun schematic (poorly drawn!~) if someone want to redraw it thats fine, let me know if you need any clarifications on parts values and such!

[jacobyjd]

doug, you are the man. Seriously.

I dig most of the designs you come up with--they're innovative, and most importantly, they're usable--plus, you show them pretty freely. Whether that's your preference or not, it's a very cool thing to do. Thanks for sharing with us--I know everyone appreciates it.

[rousejeremy]

I've built pretty much everything I can find of yours Doug, and love them all. Thanks for this too!

[John Lyons]

Are the two pots on the left top the dual gang 5k?
Then the pot in the middle is the 10K?

Crazy looking schematic, thanks though!

john

[Ben N]

Pretty crazy stuffand all out of two transistors (alright, 3 if you want to be a stickler), although you can still hear the Bazz Fuss soul of the thing coming through. Doug, nice to see you popping by now and again. That schemo reminds me of artsy short animated films from the '50s with bebop and experimental jazz soundtracks, all angular and monochromatic figures at crazy angles. But you know what? I've seen plenty of professionally drawn schemos that were harder to read, so no complaints.

[earthtonesaudio]

But you know what? I've seen plenty of professionally drawn schemos that were harder to read, so no complaints.

So true.   

Thanks for sharing again, Doug!

[doug deeper]

it really is quite different in operation to the bazz fuss, the first stage isnt really providing any of the drive, it cuts gain as a matter of fact!
all the drive is from the second stage/diodes.
the fun thing about this circuit is that is FEELS like you're playing a clean guitar, there isnt any added high gain sustain, because it actually has way less drive then it sounds like thanks to the filter sounding a bit synthy.
also! i just drew the schematic up quick like last night while waiting to watch lost!
i dont work off that or anything! i dont even think i have it drawn out anywhere?
and one final note!
on the second stage, some times the two resistors coming from the base of the transistor are 470k and 47k, all depends on what i grab really, doesnt sound much different in the long run, but options are great!

[SpencerPedals]

I just built the Peace Gun on vero and it works a bit and the knobs do their respective thing, but I'm not getting the upper octave thing going on and the volume needs to be cranked to get to unity.  On some settings the high frequencies are killed enough so the B and E strings don't even register.  The voltage readings at Q1 base are about 1.3v and Q2 are about .7v...anyone have any pointers as to what those should approximately be and where to look at this point?  I've double checked resistor values and connections as well as diode orientation.  I currently have the clipping diodes mounted elsewhere and am using non-4001's for those, but clipper flavor shouldn't make a difference.  I did use a 4001 in the signal path.  Any help would be appreciated...it sounds to me like a transistor biasing thing, but I'm not sure what the readings should look like.  Thanks again,

Steve

[rousejeremy]

What vero layout did you use?

[ppatchmods]

anyone try it with a bass yet? i wonder if it will let a good amount of low end through?

[SpencerPedals]

I used a layout from another site.  Not sure I can post that here.  I've triple checked the resistor placement in it and they're right, per the schematic above.  I have no idea what the voltages on something like this should look like.  If anyone has an idea regarding that sort of thing, I'd be very appreciative of any help.

And I'm sure you could probably just raise a few of the cap values if you wanted to make a bass(ier) version.

[Scruffie]

I'm sure linking to it is ok, even though it isn't mine either,
http://www. FxxxSxxxxBxxxx   .org/viewtopic.php?f=7&t=5550