NEED HELP Breadboarding a Silicon Fuzz Face Pedal

[feddozz]

Be careful 2n3904 are nPn transistors. I wonder why the LPB1 was not working. 3904 are the right  transistors for it.

Really the fuzz face iso youth schematic for npn or pnp transistors?

[thermionix]

That will do it!  Easy mistake to make, the numbers are so similar.  If those trannies aren't fried, you can still try them out.  Just swap the + and - leads of the battery, and the polarity of the two electrolytic caps.

[bonzoboi]

@thermionix I replaced the transistors with new ones and did what you said to do, and this time I got a consistent hissing/buzzing coming from the amp, and when I touched the tops of the caps or any of the pots or jacks that sound smoothed out. But still no signal from the guitar. Hmm...

[Electric Warrior]

Now that the big problem is out of the picture it's probably something minor.
How are the voltages now? Maybe they can help locate the error.

[Fndr8875]

just for future reference about measuring pot values i meant at end of wire that is soldered onto lugs. I didnt hink that was your issue as your close up pics looks really shiney. Ive soldered full sized pots a ton of times on guitar and never have any issues but for some reason the 16mm pots gave me hell for a while, prob to much solder and it would get into or under the part of pots where the lugs attachs, where the round holes are. Well glad you made some progress as far as identifying transistors. Some of ones ive ordered the white print seems to come off very easily if handled to much, im and unorganized mess so u can imagine how itcan make getting all your parts together and pain once youve accumulated a lot of parts and dont have a organizational system. Good luck, will wait to see how it turns out

[duck_arse]

bonzo (I'll try and be gentle), I've always avoided using the 2N29xx and 2N39xx cause I can't remember wwhich is NPN and which is PNP, as I was brought up using the BC series, which are also pinned backwards.

but, now you know why we ask those questions when we ask those questions.

[bonzoboi]

Hello all!

I have returned to this project now that I have received my new, hopefully correct transistors.

I inserted my 2N3904 NPN silicon transistors into my breadboard which has successfully been tested for continuity and followed the layout at http://diy.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm, and I am still not passing a good signal.

What has changed from before is that now, when my breadboard has power and is hooked up a guitar and amp, it makes a loud, continuous hissing noise, but does not pass the guitar signal. I also ordered some 2N2222A germanium transistors, and tried replacing one of the 2N3904 transistors with one of these, and also tried replacing both silicon transistors with these germanium transistors, and when I did both of these things, the hissing decreased, but still no signal was passed from the guitar. It seems the volume and fuzz knobs are somewhat working, in that when I turn them down, the volume of the hissing will disappear.

Here are my voltage readings when I am using 2N3904 silicon transistors for both Q1 and Q2 on my board:

Voltage at the circuit board end of the red battery lead = 9.50 V
Voltage at the circuit board end of the black battery lead = 0.00 V

33K R
BottomLeg = 9.50 V
TopLeg = 1.40 V

100K R
LeftLeg = 0.63 V
RightLeg = 0.75 V

8.2K R
LeftLeg = 3.71 V
RightLeg = 9.27 V

330 R
BottomLeg = 9.50 V
TopLeg = 9.28 V

0.01 mF C
LeftLeg = 9.27 V
Right Leg = 0.00 V

2.2 mF C
PositiveLeg = 0.63 V
NegativeLeg = 0.00 V

22 mF C
PositiveLeg = 0.75 V
NegativeLeg = 0.00 V

Q1 T
C = 1.40 V
B = 0.63 V
E = 0.00 V

Q2 T
C = 3.73 V
B = 1.40 V
E =  0.75 V

500K P
CCW = 0.00 V
W = 0.00 V
CW = 0.00 V

1K P
CCW = 0.00 V
W = 0.75 V
CW = 0.75 V

Also, if you are seeing this thread for the first time, I have posted pictures earlier on of my breadboard layout, which has not been modified since I changed out the transistors. Here they are:

Over-view: http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/20170127_140911.jpg.html
Closer over-view: http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/20170127_140957.jpg.html
Side-view: http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/20170127_141021.jpg.html

[sominka]

Fuzz face is really simple. Follow your schematic. If you make a mistake look at it again and retry.

[bonzoboi]

@sominka, I wish it was that simple. I agree, the breadboard and circuit are very approachable, but I have gone through multiple iterations of re-breadboarding this circuit, and still have not been able to pass a signal.

Here are my voltage readings with the germanium 2N2222A transistors used for Q1 and Q2:

Voltage at the circuit board end of the red battery lead = 9.50 V
Voltage at the circuit board end of the black battery lead = 0.00 V

33K R
BottomLeg = 9.50 V
TopLeg = 1.36 V

100K R
LeftLeg = 0.60 V
RightLeg = 0.74 V

8.2K R
LeftLeg = 3.74 V
RightLeg = 9.28 V

330 R
BottomLeg = 9.50 V
TopLeg = 9.28 V

0.01 mF C
LeftLeg = 9.28 V
Right Leg = 0.00 V

2.2 mF C
PositiveLeg = 0.60 V
NegativeLeg = 0.00 V

22 mF C
PositiveLeg = 0.74 V
NegativeLeg = 0.00 V

Q1 T
C = 1.36 V
B = 0.60 V
E = 0.00 V

Q2 T
C = 3.74 V
B = 1.36 V
E =  0.74 V

500K P
CCW = 0.00 V
W = 0.00 V
CW = 0.00 V

1K P
CCW = 0.00 V
W = 0.74 V
CW = 0.74 V

[feddozz]

I am getting suspicious. Where did you get those 2n2222a germanium transistors?

Was it someone with a big copper coil thing that sold them to you?

[bonzoboi]

I got all of my transistors from taydaelectronics.com

[sominka]

http://effectslayouts.blogspot.co.uk/2014/11/npn-fuzz-face.html

[slacker]

Your voltages look alright, the collector of Q2 is a bit low but it will work, I also can't see anything wrong with the layout. This is probably a stupid question but have you tested that you haven't got a problem with the jacks, try plugging the red and blue wires from your jacks into a spare row on the board to connect them and play something just to make sure they're ok.

2N2222A are silicon transistors by the way, I think that is why feddozz is asking where you got them.

[Electric Warrior]

Your voltages look alright, the collector of Q2 is a bit low but it will work,

I'd say it measures just as expected. With Q1C sitting at 1.4V, 3.7V for Q2 is in the right ballpark. That's how low gain silicons will bias in this circuit. Higher Q1C and lower Q2C than with high gain transistors.
Dallas-Arbiter only used low gainers for a very limited time, but those were in the same ballpark as well.

This is probably a stupid question but have you tested that you haven't got a problem with the jacks, try plugging the red and blue wires from your jacks into a spare row on the board to connect them and play something just to make sure they're ok.

It's not a stupid question at all. With the voltages being dead on, the problem is happening before or after the transistors. Other than the jacks, the volume pot and their wiring I'd make sure to check if the input and output caps are connected correctly.

2N2222A are silicon transistors by the way, I think that is why feddozz is asking where you got them.

They sure measure like low gain silicons in circuit.

[duck_arse]

is there any chance you have wired to the ring connection of the left-most jack instead of the tip connection?

[bonzoboi]

THE PEDAL WORKS!!! I REPEAT!!! THE PEDAL WORKS!!!

I had my stereo jack wired incorrectly!

Thank you all so much for the help!

Now, I'm going to move forward and solder it to some perfboard and house this baby.

[Electric Warrior]

Congratulations! Now that it works you can start experimenting. Try matched and mismatched transistors and see what you like better. You could also mess with the bias.

[bonzoboi]

@ElectricWarrior, I did some experimenting and found the 2N3904 transistor at Q1 and the 2N2222A transistor at Q2 to be the best combo. What do you mean when you say, "mess with the bias"?

[Electric Warrior]

Excellent! Great to hear that you found a combination that works well for you. This circuit doesn't really need any modification to sound good as long as your transitor selection is within reason.

You could still try larger resistors on Q1's collector to see how you like it biased a little (or much) hotter. Or compare that with tweaking Q2's collector resistor. Or try higher gain transistors. Or germaniums. There's a lot of stuff you can audition. The fun is only just beginning.

[rutabaga bob]

Oh, yeah!  He's hooked!