Chuck D. Bones
Circuit Wizard
The leakage is critical to getting the trannys to bias correctly.
Are you running a 1.5V or 3V rail? I've tried it at 9V and did not like the tone.
MODIFICATION The FZ-1 - CB style
- Thread starter Chuck D. Bones
- Start date
Are you running a 1.5V or 3V rail? I've tried it at 9V and did not like the tone.
Coda
Well-known member
I went with the Mister Fuzz schematic, so it’s 9 down to 3v. I’ve gotten pretty close, but not close enough to make it permanent. I had the same issue with my MKI build. Part of the fun, I suppose…
Chuck D. Bones
Circuit Wizard
Coda
Well-known member
Hmm. Maybe I’ll swap it up. I’ll either end up with one good one now, or 10 good ones.
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Chuck D. Bones
Circuit Wizard
You can tweak R7 to dial-in Q2, R8 and/or R9 to dial-in Q3. Even with the resistor tweaking, not every transistor will work well for Q2 and Q3. Bear in mind that the ATTACK pot varies Q2's bias, so adjust R7 to get the best range on the ATTACK pot.
As a point of reference, on mine Q2-C runs from 3.00V (ATTACK min) to 1.77V (ATTACK max). Q3-C runs at 1.97V. Vcc = 3.07V.
BTW, I only tried the circuit from post #14 on the breadboard. My pedal uses the schematic from post #1.
Coda
Well-known member
I’ll have to get back on it and start with some new measurements. It got to the point that whenever I got a new batch of transistors I would try a few. Like I said, maybe I’m being too picky and should just commit to something that’s close enough.
Chuck D. Bones
Circuit Wizard
When it's working right, you'll know it.
Coda
Well-known member
I dug my breadboard FZ-1 out. Right now I get the following voltages: Q2= 3.2 (min) 2.9 (max), Q3= .39. VCC is 3.2v.
Chuck D. Bones
Circuit Wizard
Q2 is hardly changing when you rotate ATTACK, that ain't right. Referring to the Mr. Fuzz schematic, make sure R5 and R6 are correct. Have you measured the HFE and lkg of Q2? You could try reducing R6 or increasing R7 (try R7 first).
Q3 is running way too hot (collector current too high). Your choices are:
1. Find a transistor with lower leakage
2. Reduce R9.
3. Reduce R8.
I'd try them in that order.
Are you sure your breadboard is built correctly?
Q3 is running way too hot (collector current too high). Your choices are:
1. Find a transistor with lower leakage
2. Reduce R9.
3. Reduce R8.
I'd try them in that order.
Are you sure your breadboard is built correctly?
Coda
Well-known member
Well, I did it. I have successfully breadboarded an accurate-sounding FZ-1. A serious bucket-list accomplishment. I read through this thread for the 20th time, pulled out a fresh breadboard, and got to work. I had to audition about 4000 different resistor values. The trick ended up being the "new" R10. Before that addition I wasnt getting anything near .7 on Q3...I was measuring like 0.035! Now everything works. Q1 is a 5457 cause it was handy (I tried to say that in my most Chuck Bones voice). It sounds very buzzy. I built mine stock...I reverse-engineered your tone section out of there. I may add it back, though. Thanks for this thread. Any chance we can get your Vero layout? I suppose I could make my own, of course...
Chuck D. Bones
Circuit Wizard
Ask and ye shall receive...
Vero is 14w x 17h
10 cuts
3 links + 2 bridges (on the Cu side)
Out board wiring is per schematic
Vero is 14w x 17h
10 cuts
3 links + 2 bridges (on the Cu side)
Out board wiring is per schematic
Coda
Well-known member
Thank you very much. I think I could easily modify that to suit my needs (eliminate the tone section)…
mzy12
Active member
Sorry, I know this isn't the point of this thread at all, but at the end of your first post on your note about PNP vs NPN transistors, you mention using a negative ground for PNP and how, for example, the Way Huge conquistador just turned the circuit, "upside down." Would I be correct in assuming this just means swapping where the 9V and ground connections normally go on the board?
Chuck D. Bones
Circuit Wizard
No.
I don't know what you do or don't know about electronics, so I won't get into a long discussion here. Study the Conquistador schematic and that should clarify things.
I don't know what you do or don't know about electronics, so I won't get into a long discussion here. Study the Conquistador schematic and that should clarify things.
szukalski
Well-known member
You need some sort of understanding of how stuff flows. A good starting place would be here:
Chuck D. Bones
Circuit Wizard
The Mizuque.com article provides a good discussion of running PNP transistors with a negative ground. Three comments:
* Unless you're building a Fuzz Factory.
- The article has the 2.2uF cap backwards on both schematics. Not that it matters much because the DC voltage across the cap <1V.
- The 20uF cap can connect to GND in both schematics. It does not have to connect to the positive rail in the PNP circuit.
- Power supply bypassing is always a good idea*. We should not depend on the impedance of the battery or power supply to ensure that the power supply rail has a low-impedance path to GND.
* Unless you're building a Fuzz Factory.
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mzy12
Active member
Just out of morbid curiosity, why is this? I know the same is said about Devi Ever's Hyperion 2 with the oscillation control. I've seen some claims about how the circuit is required to be 'unstable' or whatever, but unfortunately for my inquisitive mind, this just isn't a good enough answer for me
There's also a 47uf bypass cap in the PedalPCB schematics for the fuzz factory, will this produce an undesirable effect on the stability control?
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