cool one knob fuzz

[duck_arse]

I put the v1 on the bb tonight. using an MJE3055 (Mot, very old, TO-127) I got too high volts, splat and fart, no gain, oh woe. with a 2N3055 (SGS, italian, TO3), all is right with the world. a bc547 (hFe 180) put the voltages about exact, but I swapped for a weird old mini-button, end base thing, marked "715F" (hFe 220) and the voltages only shifted a little, so still good.

and an input cap of about 22nF sounds good.

[duck_arse]

well now, I went looking and couldn't find a datasheet for the Motorola MJE3055/2955 in the TO127. anybody have one? I did see someone on ebay selling 3055's for 15$US each. and not even the gold pin ones.

[hymenoptera]

well now, I went looking and couldn't find a datasheet for the Motorola MJE3055/2955 in the TO127. anybody have one? I did see someone on ebay selling 3055's for 15$US each. and not even the gold pin ones.

In this application (very low power), it should be the same as any other 2n3055 package.

https://en.wikipedia.org/wiki/2N3055

[duck_arse]

...... but with more mojo.

and I happen to have a second TO127 part, which I tested in circuit today. all voltages close to spot on.

[Ben Lyman]

BAM! First try... Thanks Gus! Loving it with a couple 2n2222s.
Got a little RF, put a 3.3k right before input cap and solved it.
Could that maybe sacrifice a little gain? I didn't notice any difference.
Sounds great, this one is going in my next Altoid tin.
Is there any reason I can't have a 100k trimpot as a set & forget volume control?

[Gus]

Ben Lyman
a 100k trim should work fine might be a little hard to get right because it is a linear taper and not a audio taper
Cozybuilder next one I build will have a 3.9k and 910 adjusting the roll off cap.
duck_arse thanks for the feedback. The 2N2222 model seems to bias in a real build as the sim

How I went about this.  I looked at the Colorsound one knob and other schematics on the web to see what people liked
I selected collector and emitter resistor values for transistor collector current.

Now because the emitter resistor is bypassed you can use R7 in the second screenshot I posted as a bias adjust.  I was simming circuits (easier than building) an worked to get this close to 100k.  So if you want different bias voltages adjust this resistor.  Look at the the pinch control in another fuzz.

A number of things set the bias in a FF like circuit the emitter resistor the feedback bias resistor the collector resistors. 
I tend to start with the collector voltage/collector current/collector resistors values and work from there.

[Ben Lyman]

any chance you could do this with a Tone Bender MKII circuit?

[Cozybuilder]

I built a modded one-knob fuzz, a few changes, but inspired by Gus, thus the name. At about half fuzz, it has a pronounced kocked wah flavor. Heres the schematic & wiring diagram:



The patina was too nice to sand off, so I took that as a motif and looked at graffiti for inspiration for the graphic & tried to give it a weathered look. Not quite done yet, right-angle RG6 connectors are on order. For the short term I made a couple of 3' cables from a 6' CATV cable, ¼" plug on the 2 cut ends, and the pedal works great. Those cables are far too stiff, so I'm looking forward to the new connectors.

The pots are below the top of the stompswitch when its pressed. They are a pain to turn now with connectors in place- I'm looking for some of that old black fabric tape they used to wrap electric wires with, wrap around for a thin knob with grip.

And the box:


And a family shot with other pedals:
 

Edit: Light plate finished:

[hymenoptera]

OMG Russ, you did it. 

You stuffed a pedal into that little tv splitter box. That is freaking awesome, man! WTG!

[duck_arse]

the pitta-patina of little feet.

handlebar tape from the cycle shop.

[Cozybuilder]

Off to the bicycle shop then- thank you DA 

[Ben Lyman]

Maybe next time you could install that in a guitar pick! 
but seriously, for grip, maybe you can dip the posts in tool handle rubber dip from the hardware store 

[Cozybuilder]

I thought I'd reached the size limit with my first 1590A (Gus' ASDF), then saw 1590LB and had to try it, but this one is the end of the ever smaller builds. Aside from being difficult to turn the controls, it violates one key thing- being able to hand it to someone and them being able to just plug in a guitar and use it. But it was fun to do 

Ben- good suggestion on tool handle rubber, thank you.

Edit-
Y'all got me thinking about what I might have around the workshop that would do- and wound up wrapping a bit of masking tape first then covering with shrink tubing- works great!

[Ben Lyman]

shrink tube!! f-ing brilliant, I love it. If the pots won't slide back out for a repair, all u have to do is slice the shrinky with a razor. very cool

[Gus]

Cozybuilder that is a small build.  I like how it lights up.

To be clear the first screenshot in this thread is the one that is a little different. I should build again with a little more drive for Q2.

The second is a colorsound one knob, VOX etc FF like with adjusted values for 2N2222s.  Nothing really new
When I build it again I will post values for 2N5089s and 2N4401 etc

Ben Lyman  I believe there i a thread about Ge transistor models for LT spice and others have posted about Si based fuzzes adjusted to more Ge like sound.  Search for piggyback and other word strings with the fuzz name and Silicon

[Ben Lyman]

Ok Gus, thanks, will do! 

[mac]

What happens when you drive a power transistor run at low collector current(about .5ma)?
What happens when you drive a larger die transistor at low currents?

Gus,
I've been using power transistors in this kind of circuits, BD237 in particular, because they have
a) high internal capacitance,
b) and hfe falls at low base currents, that is , hfe is a function of ib.
I mean, hfe falls faster than small signal transistors, 2n2222, etc.
IMHO, when you place a TIP, BD, etc at Q1 and you roll back the guitar volume, gain drops faster.

Try BD237, mine are a bit hotter than TIPs, and cheaper.

mac

[Gus]

Built another version of the circuit in reply 10
Used two 2N5089s about 470 and 490 hfe
Q1 10k collector resistor
Q2 3.9K and a 910 ohm with a .022uf across it in the collector
220K feedback resistor
More buzzy than the PN2222 versions I built

next build is an one knob 2n3904 version followed by 5 control FF like circuit I built before and people like, after that a 6 control FF like build

[Gus]

Built a few more based off the reply 10 circuit

For fun try 1uf, 10uf, 47uf, 100uf and 470uf for the 1k emitter bypass cap
They try different input cap values(you could start with the SD Tweak Fuzz input values) with the different emitter bypass cap value you can get different frequency EQ curves with the guitar volume

[Gus]

Built another 2222 version
.22uf input cap
120uf emitter bypass cap
910 ohm bypassed with .022uf and 3.9k collector section at Q2
1uf film output cap to a 100K volume

So much IM you can get lower frequencies