Wyllie Moonrock

[RRJackson]

I put together a version using a PNP transistor for Q2, which allows the use of a Germanium transistor. This one has Gain, OFS (Octave-Fuzz-Swell), Tone, and Volume pots, and a toggle to add octave to the swell. Its a super versatile circuit, currently I have a Russian GT308V in Q2, it sounds a little different than a silicon PNP in that slot, but not as much as you might imagine.

That is insanely cool. Super cool. All out of words for how cool that is. 

- Rob

[Fast Pistoleros]

I put together a version using a PNP transistor for Q2, which allows the use of a Germanium transistor. This one has Gain, OFS (Octave-Fuzz-Swell), Tone, and Volume pots, and a toggle to add octave to the swell. Its a super versatile circuit, currently I have a Russian GT308V in Q2, it sounds a little different than a silicon PNP in that slot, but not as much as you might imagine. The Q2 is in a 4-place SIP socket wired E-C-B-E so that different pinout PNPs may be used, the other transistors are soldered direct.

This is housed in a 1590B wedgie enclosure http://www.diystompboxes.com/smfforum/index.php?topic=110590.0

Schematic:


Build:


Gutz:

that is magnificent , awe inspiring work right there. this is as good as it can get ..except I would want mine in blue which is my favorite color lol

[Keppy]

Germanium fuzz experiments sound like fun! I have a couple questions about what you did.

1) Shouldn't the 130k resistor between Q1 & Q2 be returned to 9v instead of ground in your circuit? (This would also require reversing the 10uF caps in between, unless the Q1C voltage is way high) I'm kind of surprised it performs similarly with the biasing as it is. Then again...

2) Why choose Q2 for the swap? That appears to me to be a phase splitter with little to no gain. It seems like you'd get more flavor by swapping either of the other two transistors. Did you try? If not, could you? For science?

[Cozybuilder]

It looks like I have a homework assignment 

I'll try PNP in Q1 and see what it does. It'll be a couple of days- other irons in the fire.....

Edit:
I just tried tying the 130K to +9V, reversing C3 and C4. Results: the circuit responded with a slight octave effect throughout the OFS settings (which it did not do before), and the swell effect was significantly reduced. The octave was excellent, but not better than before.

Don't know why I didn't think of trying PNP in the other positions , but playing with Q1 will be next.

[duck_arse]

I listened to dino's tooth's last night - now I know what you mean by swell.

[GiovannyS10]

Oh mu God! I really love this pedal! 

[chuckd666]

I put together a version using a PNP transistor for Q2, which allows the use of a Germanium transistor. This one has Gain, OFS (Octave-Fuzz-Swell), Tone, and Volume pots, and a toggle to add octave to the swell. Its a super versatile circuit, currently I have a Russian GT308V in Q2, it sounds a little different than a silicon PNP in that slot, but not as much as you might imagine. The Q2 is in a 4-place SIP socket wired E-C-B-E so that different pinout PNPs may be used, the other transistors are soldered direct.

This is housed in a 1590B wedgie enclosure

Gutz:

Damn Cozy, I gotta get a drill template for the top mounted jacks on that 1590B. I love it, but my drill ability is so shameful.. I guess I gotta measure more.

[Cozybuilder]

chuckd666- I know there are a lot of different ways to make accurate measurements, but heres an OCD method. First I decide where all the fixed box components will go- pots, jacks, switches, LEDs, circuit card with a way to solidly attach it etc, draw it, remeasure, and drill for one or two components at a time & test fit, checking for clearances for knobs and toggles and their operation. Sometimes I need to fill a hole when the part needs to be moved (JB Weld to the rescue). When everything is in place and I like it, switches are operable etc, then I cut a perf and the mounting system for it (it might be on-board pots, standoffs, or brackets). Once I know the size and locations of interferences for the circuit card, I do the layout.

For the wedgie 4-knob MoonStone, the hole pattern that I used is as follows:



I set the measurement with a dial caliper with a depth gauge, like this one:


Then set an adjustable square to that dimension using the depth gauge:


Then stick a piece of masking tape on the box, and mark a cross for the hole center. Once the holes are all marked, I check it, erase the mistake, and re-measure etc until its right. To drill accurately, I use a 0.5mm drill bit to align it in my drill press- it would be fine to simply use a sharp hole punch and drill a small pilot hole. 1/16" is the largest pilot I'd use, then progressively step up the hole diameter. Tedious but accurate, and I'm sure there are better ways.

[digi2t]

If you use unpainted enclosures (like myself), you can forego the tape. Fine point Sharpie direct on the enclosure, which washes off completely with a touch of brake cleaner.

[chuckd666]

Excellent info. I think part of my problem may be lack of tools (there I go blaming tools again...) but those calipers seem pretty vital for tight work like this. Thanks for the walkthrough! Appreciated.

[digi2t]

One of my favorite tools for marking up off an edge...



Machinists pocket ruler. Not expensive. The movable guide acts as a set stopper for quick transfers.

Also handy for measuring string to fret height.

[Cozybuilder]

Keppy sent me down the rabbit hole with the comment on biasing. After measuring the voltages on Q1, I was surprised it worked too. So the first objective was to get a better bias voltage spread, which got me to tinkering and eventually wound up with 1M feedback between B&C, which gave a little better sustain as well as an acceptable voltage spread. Unfortunately, it also gave a swell effect across the full range of the OFS pot, which in turn required more fixes and testing, but with the mods it all worked well with an NPN in Q1, and AB'd nicely with the 4-knob posted earlier. There is still a swell effect with full octave, so the octave switch could be eliminated. If you back off the octave, the swell disappears and you get decreasing amounts of octave with the fuzz. When the OFS is rotated close to the swell side, you get increasing swell without octave.

The next step was to redo the configuration for PNP. The same basic component values worked well for the silicon (swapping V+ & ground at Q1) so I tried a Germanium. I fully expected to have to tinker with bias resistor values, but found that was unnecessary. The silicon PNP AB's well with the 4-knob NPN build, while the germanium gives a different sound. This is a much more distinct difference than the results from the Q2 PNP germanium posted before. Anyhow, as drawn below it works well with either Germanium or Silicon with the same support component values. I was hoping to be able to switch between Si and Ge with a SPDT, using as many components for both as possible, but the leakage of the Germ plays havoc with the Si, so one has to switch out 2 legs to isolate them, necessitating a DPDT. In the end, the Germanium transistor gives a warmer sound than the Silicon, and volume levels are very close.

Why switchable? With the concern about germanium not performing well on a hot stage, I wanted the player to have the option of switching to silicon and get essentially the same sound.

This is what is on the breadboard now:



Edit: Same inductor as before [42TL019 primary (10K side)]

[RRJackson]

Why switchable? With the concern about germanium not performing well on a hot stage, I wanted the player to have the option of switching to silicon and get essentially the same sound.

Not to add any depth to that rabbit-hole, but this seems to work well for keeping Germanium transistors at a desired bias voltage under changing temperatures.



-Rob

[Cozybuilder]

A small but important correction to the schematic I posted yesterday. The 22K connecting OCF lug 3 and the diodes (D5 & D7, D8) is drawn wrong, it should be in series with cap C7 and OCF lug 3. This allows enough drive from the octave phase splitter when the OCF wiper is turned towards lug 3 that you get the octave swell function. Essentially the resistance at full rotation becomes 22K, not 44K, allowing the swell with octave. The other end of rotation to swell is not affected by this change. See below:

[Cozybuilder]

Playing with the circuit on the breadboard again. I wasn't satisfied with the transition from Octave to Fuzz- there was always a bit of the octave in there, and my efforts with various low resistance and capacitors didn't do the job. Suddenly it occurred to me that the OFS pot was oriented wrong, so I redrew it and breaded this new one, played with some values, and wound up with something closer to what I was looking for. A 1M pot works well, but there was too little variance at the ends where you need an audio taper at each end to get a lot of tonal variety, so I tried a linear 500K which worked much better. I tried sticking a 470K resistor across the pot (1-3), which was too low, but a 1 M got me close to the audio taper at each end I was trying for, without bleed through. The schematic below needs 2 things-
  1: 1M across OFS lugs 1-3
  2: a SPST across that 1M to give an even greater pallet of tone & swell

[Droogie]

Just finished the deluxe version and I love this thing!

I ended up using 2n3904 in Q1 and 3; BC547 in Q2; TL002 for the trans (had to tweak the vero layout since the 10k side is opposite to the TL018).

Really nice octave and fuzz, but that swell is just insane!

Thanks for all of the hard work you guys put into this!

[Cozybuilder]

I've been busy trying different things to try to improve the sustain, separation of effects, and believe this one does it. There are quite a few changes from what was posted earlier, this is much better. A couple of people have told me they prefer a minimal of controls, 2 knobs usually, but a toggle is OK too. I liked the sound of the MoonStone without the tone circuit, but then why shouldn't you be able to dial in your tone? Usually once the tone is dialed in though, I leave it alone, and think maybe others do the same. So, I thought that moving that control to the circuit board made sense- set the tone, be done with it. Can change it if you want. So here is a simple 2-knob-1-toggle pedal, with set & forget tone trimmer, with an incredible amount of versatility between the OFS pot and Octave/Swell toggle.

Schematic & pedal:

[duck_arse]

final? no ofs wiper R?

you beaut!

[Cozybuilder]

final? no ofs wiper R?

you beaut!

The OFS wiper R was meant to take an A pot and emulate a W pot- but the parallel resistance when the wiper was towards the Octave side introduced swell (a lot of it), and I found that its best to just get rid of that R. Now if I could only find a 1M W-Taper pot (Steve at Small Bear looked into it). This was fixed after the build- for the sharp eyed, the 270K has been isolated from the circuit by clipping the connection to diodes 5, 7, & 8.

[digi2t]

Now if I could only find a 1M W-Taper pot (Steve at Small Bear looked into it).

I don't think it will get any better than this. 

http://www.ebay.ca/itm/Potentiometer-1M-Ohm-W-Taper-Center-Click-/120669464659

Russ, I can buy some, and send them down back to you with the pedal. They're right here in Quebec. Bonus!!