This Week on the Breadboard: Shin-Ei FY-2 Germanium

[Chuck D. Bones]

I was looking for something to do with some PNP Ge transistors and ran across this thread in DIYSB:

https://www.diystompboxes.com/smfforum/index.php?topic=92533.0

The Ge version of the FY-2 is rare and very different from the Si FY-2. The Ge FY-2 is a FuzzFace derivative. Here's what I breadboarded:


As described by Luciferstrip in the link above, this thing is LOUD and NASTY. I flipped everything upside down so I could have a negative ground with PNP transistors. This could just as easily have been built with NPN trannys. I added R1 to tame oscillations and C4 to reduce the high-order harmonics a bit. I increased C5 from the original 2nF to get a little more mid and bottom. I changed the VOLUME pot to A-taper, it was originally B-taper. The FUZZ control varies both the gain and the bias. The 50K pot gets it pretty close to gating when dimed. The sweet spot, if you can call it that, is around noon. The MP20s were selected for low HFE, 40 and 43. Leakages were under 100uA, although I doubt leakage on Q2 matters much. This thing is very responsive to picking and the guitar's volume setting. Not really my kind of fuzz, but some of you may like it and it's definitely worth breadboarding.

 

[steviejr92]

Well now I know what to breadboard in the coming days! Being a fuzz face derivative it looks pretty simple as well! Going to have fun with this one!

 

[Chuck D. Bones]

Only 15 parts (not counting off-board stuff like pots, switches & jacks), it qualifies for the Express Lane.

If you want to get some gating, try reducing R5 a little.

 

[steviejr92]

Only 15 parts (not counting off-board stuff like pots, switches & jacks), it qualifies for the Express Lane.

If you want to get some gating, try reducing R5 a little.

Bookmarked for when im going to tackle it as a matter of fact since my current build is held up i think im going to tackle this now!

 

[steviejr92]

When you say you flipped everything upside down to accommodate for the PNP tranny how exactly is that done? I have only NPNs and would like to know how this is done!

 

[Laundryroom David]

When you say you flipped everything upside down to accommodate for the PNP tranny how exactly is that done? I have only NPNs and would like to know how this is done!

Look into the mirror mwahahahaha. Kidding. I am not an expert. But I have breadboarded and built a bunch of PNP projects. I am willing to bet that others, including @Chuck D. Bones will have much better explanations. But here’s what worked for me.

With PNP, you need to reorient your brain to thinking in terms of -9v and +ground. Polarized components get flipped, emitter goes to + ground and collector goes to -9v.

Plug the + of your battery to the - rail, and then - of your battery to the positive rail.

Also remember that if the 1 of a pot goes to ground on your schematic, that does in fact mean it goes to + ground on your breadboard.

I would also say don’t try using -9v from a power supply until you get a PNP project up and running by battery.

 

[steviejr92]

Look into the mirror mwahahahaha. Kidding. I am not an expert. But I have breadboarded and built a bunch of PNP projects. I am willing to bet that others, including @Chuck D. Bones will have much better explanations. But here’s what worked for me.

With PNP, you need to reorient your brain to thinking in terms of -9v and +ground. Polarized components get flipped, emitter goes to + ground and collector goes to -9v.

Plug the + of your battery to the - rail, and then - of your battery to the positive rail.

Also remember that if the 1 of a pot goes to ground on your schematic, that does in fact mean it goes to + ground on your breadboard.

I would also say don’t try using -9v from a power supply until you get a PNP project up and running by battery.

Awesome! So im not gonna lie i looked it up right after i posted this i got the gist of it but having your reply solidified things. Your info was definitely a help!

EDIT: the way im going to go about it is im going to breadboard it as is, then make all the necessary changes that flip the circuit polarity.

 

[Laundryroom David]

Awesome! So im not gonna lie i looked it up right after i posted this i got the gist of it but having your reply solidified things. Your info was definitely a help!

EDIT: the way im going to go about it is im going to breadboard it as is, then make all the necessary changes that flip the circuit polarity.

Exactly.

EDIT: I think my brain has gone bye bye for the night so I’m going to just stop talking. 😂

 

[steviejr92]

Exactly.

EDIT: I think my brain has gone bye bye for the night so I’m going to just stop talking. 😂

Well you helped regardless!