No sound on a DIY Bazz Fuzz (1st project)

[FredG]

Hello everybody,

I'm new to this hobby and after browsing the net on DIY pedals, it's quite clear that a fuzz pedal is the place to start.
So I tried to build this one :
https://tonereport.com/blogs/do-it-yourself/your-first-diy-pedal-project-were-building-a-bazz-fuss

The dry signal is ok, and when I hit the footswitch the LED lights on, but there is absolutely no sound coming out.

Here is the components I used :
- Diode BAT41
- Resistor 10KOhm 1/4W
- Transistor BC517 (npn)
- Capacitors 470nF and 100nF

I have already remake a second time the circuit board with new components, just in case one of them was the issue, but the problem is still the same.
I noticed a difference in the wiring of the pot between the schematic and the pictures in the notice. I tried both options for the same result : no sound when it's on.
Maybe the resistor and/or the capacitors are the problem as they don't look the same at all as the ones in the notice

Here are pictures of the project, do you see anything I did wrong ?





Please note that I'm very new to this and know nothing in electronic (and that english is not my native language ).

Thank you very much in advance for your help.

[Slowpoke101]

Welcome to the forum.

From a quick look at your pictures I can see that you have the transistor in backwards. The BC517 has different pinouts from the specified transistor. Take it out and rotate it so the flat face of the transistor faces the BAT41 diode.

[FredG]

Thank you for this answer Slowpoke101. 
I tried with the transistor facing the BAT41, but there is still no sound. But when I turn the pot to the maximum there is now a very light humming.

I see in the comments below the instruction notice of Tonereport that many people had an issue with the volume being very low, even with the pot on the maximum position... Is it due to a wrong naming of the wires in the schematic and then a wrong connection to the pot or the footswitch ?

[Slowpoke101]

Check for construction errors. Even on simple builds an error can happen.
Can you upload a picture of the solder side of the board?
Also can you take some voltage measurements of the transistor leads?
One other thing to check - what is the value (resistance) of the output level potentiometer?

[FredG]

OK OK
I was so excited with this, I forgot to solder the center lug of the transistor 

But good call from you, the transistor is indeed facing the wrong direction on the schematic ! (I just tried it both ways)

I also change the resistor from 10k to 100k as I red somewhere that with a 100k potentiometer you should have a 100k resistor... 

The sound is a little bit too crapy now. I will try with different component here and there, experiencing a bit.

Last question : the potentiometer is also changing the output volume.
What can I do so it only mix the distortion in the dry signal without affecting the volume ?

Thank's again for your time to help a newbie ! 

[antonis]

Set BC517 reversed, as Slowpoke already said, 'cause MPSA13 (E-B-C) & BC517(C-B-E) have different pin-out..

Check for proper diode polarity 'cause BJT shouldn't be biased at all in case of BAT41 reverse placing..
(check also for good diode status with a DMM - about 600mV forward voltage drop & no reverse voltage drop (open)..)

Try to lower Collector resistor (10k) to 1/5 - 1/10 (2k2 to 1k) due to significant minimum h_FE difference between MPSA (β=5000) and BC517 (β=30000) 'cause your BJT might be saturated..

edit: I've right now seen you've wrongly wired OUT (pot middle lug) and IN..!!
Disconnect the switch bottom-right white wire from pot middle leg and connect it to PCB input..
Disconnect white wire from PCB IN and connect it to pot middle lug (OUT)..

P.S.1
Your 3PDT switch wiring seems to be not correct 'cause it grounds OUT when by-passed (not necessary due to permanent grounding via Volume pot) and leave IN open/floating (prone to clicking) 

P.S.2
Welcome..!! 

[antonis]

Are you sure your pedal works with the existing second picture wiring... 
(In & OUT are shorted when effect ON..)

edit: My bad, I considered stereo jack as Input (as it's usually wired..)

[Slowpoke101]

Good that you found the missed solder joint 
Changing the 10K resistor to 100K probably will make the circuit sound terrible when using the darlington transistor. Have a read of this webpage http://home-wrecker.com/bazz.html. It may help make things a bit clearer.

The potentiometer is meant to vary the output volume level. It is not meant to vary the fuzz intensity. The home-wrecker page shows a circuit that can do this - an additional control named "Dirt" is placed on the transistor's emitter. Experiment with the circuit and see what you can get it to do.

Mixing the dry signal with the fuzz output (wet signal) is a bit more complicated. A simple mixing circuit probably would not give sufficient isolation of the input to the output. Perhaps another forum member has some suggestions for this one.

Antonis has made some very valid and interesting points.

[FredG]

Thank you for the answer Antonis !
I tried the changes of wiring that you proposed, but there is practically no sound coming out...
Just to be sure I understood you well for the changes, here is the actual wiring (not working) :


I have absolutely no clue how a 3PDT switch works. I was just following the instructions in the DIY link.
Do you have a schematic on how to wire it other way ? (or a link that explains how it works for noobs)

What do you call BJT ? (sorry : noob + french speaking makes it hard for me )

And for your second post : yes the pedal works fine with the wiring on the second picture. 

And thank's to both of you, I  will change the resistor to the initial 10k value or lower.

For the volume question, now that this first experiment works, I will look for a 2 knobs pedal that blends the dry and wet signal.

Glad I found this awesome forum with quick and gentle feedback, you rock !! 

[antonis]

I tried the changes of wiring that you proposed, but there is practically no sound coming out...

Of course it doesn't..!! 
(plz see my edited previous post..)

I have absolutely no clue how a 3PDT switch works. Do you have a schematic on how to wire it other way ?

There are many wiring ways/options according to desirable In/OUT grounding (or not..)

My best preferable is :



or




You better utilize the following complete enclosure wiring with indicator LED anti-pop for your next builds..!! 
(much more solder/wire/item trouble compared to a SPST signal switch but you'll be rewarder with peace of mind and many nights long lasting blissful sleep..)

What do you call BJT ?

Any Bipolar Junction Transistor to discriminate it from any Field Effect Transistor (FET) or any Unipolar Junction Transistor (UJT)..

But if you prefer to call them Myriam, Jenna and Natassa respectively, it should be fine with me..!! 

[FredG]

Thank you for these schematics, Antonis. Very useful !!
And thank you for your time and your advice !

[Marcos - Munky]

Based on this wiring:

You need to swap the wire that goes to board in and the one that comes from board out (middle lug of the pot).

Post a picture of the solder side of the board. Maybe that's where's the problem.

Also, be sure you have the cables connected correctly. Looking from the point of view of the picture, input jack is the left one and output jack is the right one. Yeah, sometimes we do the dumb mistake of reverse the cables and spend hours debbuging the circuit

[antonis]

We've already dealt with that, Marcos.. 
(no wiring problem - simply IN comes from mono jack..)

[Slowpoke101]

FredG's confusion with the wiring of the stompswitch stems from the published article itself.
Below is an edited version that may help;

[Marcos - Munky]

We've already dealt with that, Marcos.. 
(no wiring problem - simply IN comes from mono jack..)

Actually, this is the exact wiring I use, with both mono jacks, but with the board in and board out reversed like I said.

But if this wiring have no problem, let's move along. I bet it should be something like a solder bridge. Waiting for an photo of the solder side.

[FredG]

Thank you every one for your help !

Just to finish properly this post, my only 2 problems were :

- the transistor I used has CBE inverted comparing to the transistor used in the schematics.
- I forgot to solder the center lug of this same transistor.

I had a lot of fun trying to change different components to find the perfect sound that I like for my bass, and now it sounds awesome !!
And coupled to a pedal with a light octaver and a light drive it's really amazing !