cool one knob fuzz

[Gus]

Build this cool one knob fuzz who needs Ge



C1 .01uf bigger will tighten up the lows works as a kind of EQ more gain below the C1, R7 RC less gain at higher frequencies (about 50K feedback) DC bias separate from part of the AC feedback because of C1
added a 47uf across R3, 2.7k
Q1 mot/onsemi 2N2222, Q2 TI TIP29
Used EH muff fuzz biasing (used R4)

Set it up as a one knob fuzz
My thinking was to use a 100K collector resistor at Q1 to limit the current drive to Q2
Made Q2 a med power device larger die being run at low collector current (more miller etc) did not need to add any roll off cap across R6, you can if you want

Sounds really good and cleans up with guitar volume

Sim was on, battery measured 9.6VDC put that in the sim and the voltages matched what I measured in circuit.  The sim screenshot  was done with 9VDC

I might add a 10k potentiometer in series with a 47uf across R3 as a gain control or I might leave it as a 1 knob fuzz

if you want a more heavy sound increase the input and/or output cap values

EDIT  I normally like a 47k feedback/Q1bias resistor because it is a "tighter" sound with more guitar volume control clean-up so I tried something different 100k sound less "tight" to me and the EH feedback/bias uses a 100K  WHY NOT let the bottom end have more gain and the higher frequencies have less
I tried a number of different values for the input, output and C1 cap values in the sims I ran, there is an number of interactions. 
I selected this set of caps after running a number of sims as a good sounding starting point.

EDIT  the 100k .01uf EQ does not work when the 47uf cap is across the 2.7K alone.  However a resistor added in series with the 47uf starting around100 ohm and larger will allow the EQ to work
So I am going to add a 100 ohms to my build and maybe this will make a good two knob fuzz 10k gain(10k control in series with a 47uf then that RC in parallel with the 2.7k) and 100k volume control

[illuminatiNPS]

Gus ,

This looks like a very well thought out variation of the muff fuzz. I'll definitely build it once I get done with ... Well you know. Need to get the program you are using too

[Gus]

A bump

I posted this to hopefully get people to do more with Silicon transistor based fuzz circuits

Picked the EH muff fuzz as a starting point

removed the clipping diodes make it more like a FF like circuit.

Look up what happens to beta/hfe when you run the first transistor at low collector currents (9VDC - 1.45VDC)/100k = the collector current.
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?

Selected valves for an added feedback path from Q2 to Q1, this is an AC coupled separate gain/EQ path from the DC Q1 bias/gain path(100k alone).

Selected the coupling cap values for a good frequency response starting point.

It responds well to the guitar volume control

[Ben Lyman]

This looks like a fun project for my next breadboard experiment. I have plenty of 2n2222's but can I use something in place of 2n3055? I have some 2n3904, 2n4401 and 2n5088's

[Gus]

Yes you can built it with two 2N2222s but that was not one of the points of this circuit
You might need to adjust the biasing, change R3's value or for more fun switch the base to ground 100k in and out of circuit

The list on the screenshot is for the collector voltages with different transistors, note the 2N2222 pair.

The use of a medium power/power transistor for Q2 is one of the things I wanted to get people thinking about.

You don't need to use a 2n3055 you can use a TIP29, TIP31 etc.

[Gus]

I am surprised at the low view count and number of people that replied

Yes it is a two transistor fuzz however I like to post things that are not total copies of something else.

Think of this as a fuzz between Ge and Si

Is the screenshot not clear?

I was thinking about why EH might have used a 100K collector resistor for Q1, so then I thought to use a power transistor for Q2 around .5ma collector current.  I have used a Silicon power transistor in a RM like treble boost and people who played it like it. Transistor capacitance can be used to an advantage
Then I adjusted the feedback a little and set it up as a 1 volume control fuzz.  If you want it maxed out (no resistor in series with the 47uf) you can omit the .01uf and the 100K
It has been built.
You can adjust the bias with the value of R3

Look up the transistors spec sheets and check out the hfe/beta vs collector current and the shape of the curve.  You should be able to find them with a web search.

[blackieNYC]

What is the power transistor is doing for you? "transistor capacitance"?

[tommycataus]

Another one for the list... I've not had great success with Si fuzzes so thus far have stuck with Ge. Would be very interested to try... Sometime I'm done with the other stuff floating about. Added to the list!! I know it'll be good since it's you Gus.

[Cozybuilder]

2n3055 on order

[Gus]

Look for the TO220 style http://pdf.datasheetcatalog.com/datasheet/motorola/MJE2955T.pdf   
TIP29 https://www.fairchildsemi.com/datasheets/TI/TIP29C.pdf
TIP31 https://www.fairchildsemi.com/datasheets/TI/TIP31C.pdf
PN2222 https://www.fairchildsemi.com/datasheets/PN/PN2222A.pdf

[Gus]

Not 100% happy with the first screenshot build at the beginning of the thread
with single coils at the bridge pickup(strat like guitar) the fuzz is weak, however with a passive bass I might leave it as it is
Q1 section might need to be adjusted for more current drive
I am thinking a 68K collector and adjusting some resistor values for bias

Just built this, seems like I have a nice control of the fuzz with a strat like guitar volume control, based off a colorsound one knob with values adjusted for 2N2222s and the interaction with the guitar volume control
omit the parts to the left of the 1meg(R9) in a build.  The 100k(R8) at the output is a 100K volume control

[Cozybuilder]

I just got through breadboarding the circuit, trying both 2N3055 and TIP31 in the Q2 slot, 2N2222 in Q1. Well, this is a keeper! I think the Tip31 was a little louder, more treble, but both sounded very good. I didn't change a single component value either. This would be a good candidate for someone wanting to try a fairly low parts count circuit in a 1590LB- the Tip31 would be an easier build  I'll have to try the 2N2222 in Q2 next.

Thanks again Gus

[Gus]

Cozybuilder

Thanks for the feedback.  Did you use a series resistor in the 47uf part of the circuit?  If you have the 47uf bypassing the 2.7k without some resistance you can remove R7 and C1 they are not doing anything.

I started building a 2nd build of the last circuit I posted I have not decided if I will try 2N3904s or 2N4401s.

EDIT forgot to add I like you used a TO3 2N3055.

Sim shows to use a 47k for R7 with 2n4401s.  Look at the hFE vs collector current in the link. https://www.fairchildsemi.com/datasheets/2N/2N4401.pdf

[Cozybuilder]

I used the first screenshot schematic, and only breaded the 2N2222 in Q1 and tried both 2N3055 and TIP31 in Q2, using an old Ibanez with Humbuckers for testing. I hadn't seen your latest posting yet. Today I'll be a little more adventurous and try the new screenshot circuit and various transistors and bias resistors etc. Am also finishing up another Protatitone Kit build today- with football games on for background music.

[hymenoptera]

I am surprised at the low view count and number of people that replied

Rest assured that we are listening. I love posts like this. I just don't have much to contribute because much of this is still beyond my skill level.

Keep it coming! 

[Kipper4]

I'm following this. Thanks Gus and Russ.

[tommycataus]

This is definitely on the list but a new arrival has meant that things are on the back burner for now... Will breadboard this at some point though

[samhay]

Gus - it's not like you to omit an emitter resistor on Q1.
I guess you could replace R3 with a C1k pot with wiper connected to C7 to give a more civilised Si Fuzz Face right?

[duck_arse]

I'm following too. and I have too many unused power transistors.

[Cozybuilder]

I've been playing around with the V2 screen shot circuit- using 2N2222A in both Q1 and Q2 slots. This is really good, Gus, thanks for sharing.

I wanted a little more volume capability, and wound up at 3K9 for R2, and 1K for R6. Why putz with a 4 cylinder when a nice V8 is available?

My tin ears like more treble, so I played with the input and output caps and wound up at 33nF input and 47nF output, and no C1. These brought it more to my liking, however there is a lot of room between the screen shot values and what I have for tweaking to your taste.

With the 47uF cap direct on the Q2E, this is like running a fuzz face with the fuzz on 10. Your guitar volume knob cleans it up, but for us with OCD and want another knob to twiddle, I put in a C1K for R3, with lug 3 to Q2E, the 47uF+ to lug 2, and 1 to ground- just like a FF. If you like all out fuzz all the time or are comfortable playing with your guitar's volume control, ignore this and keep the 1K.

Its a really good sounding Silicon circuit, well worth your time to breadboard and play with. And I might have a box to put it in