bazz fuzz issues

[Jan Irace]

I am building a Buzz Fuzz (yes a really simple pedal), it lets pass my guitar signal only when I touch the pot (so I'm guessing it's grounding issues), how do i fix this... I have never (in four years of trying) managed to make a guitar pedal, I have managed non audio related stuff but never a guitar pedal WHAT AM I DOING WRONG!?

[mth5044]

Welcome to the forum.

Can you post detailed photos of your board and wiring? If you have a multimeter, transistor voltages night be helpful.

[Jan Irace]

yes I do have a multimeter, the transistor I'm using is an S8050 and the diode is a 1N4007

[rankot]

Is your PCB ground connected to both audio ground as well as to power ground?

Is your potentiometer functional? Is it soldered well? What about wires to pot? Maybe it is loosing contact somewhere, so when you touch it, loose contact gets connected.

[Kipper4]

Welcome Jan.

Can we see the underside too please.

Can you take some dc voltages on the transistor legs.
This will tell us if the transistors voltages look in the right parish.
Maybe pinpoint something else.

Don't worry it's just like building non audio stuff but with audio overlaid.

When you touch the pot and it passes signal is it clean or fuzzy?

[duck_arse]

please post the actual circuit diagram you are working from. you say "S8050" transistor, which is PNP on my datasheet, the usual bazz calls for npn.

also, welcome.

[antonis]

Your prototype board is convenient mostly for power circuits build..
(large diameter holes used with light leg width items are prone to cold-joint..)

Also also also, wellcome..

[Jan Irace]

yes the s8050 is a pnp transistor it was labelled npn on the package and I didn't think to look up the data sheet... my bad

[antonis]

Wrong transistor placement doesn't enlighten the only_pot_touch_signal_pass mystery, does it..?? 

[Marcos - Munky]

I guess it's a grounding issue. Did you connected all the ground points together? There's a few of them: board, potentiometer, supply, input jack and output jack. They all need to be connected together at one point. You can connect them all to the board ground, for example.

Also, post more photos of your board and connetions. It seems you've changed some things, since the layout have 3 rows and you've used 5 (if my eyes are good), and also you've used an extra eletrolytic.

[Jan Irace]

I have used five rowes of the protoboard just because it was easier to layout, my protoboard has got no connections every hole is isolated... yess all the grounds are well connected (tested that), the transistor is a pnp instead of a npn because of bad labelling (I will change that the the recomended transistor)... I have to electrolytic caps because I didn't have any 4.7 caps so I put two 2.2 caps in series making basically a 4.4 that is close enough to a 4.7....
I will have photos of the underside shortly

[antonis]

I didn't have any 4.7 caps so I put two 2.2 caps in series making basically a 4.4 that is close enough to a 4.7....

You've result in 1μ1 and not in 4μ4..!!
(caps in series "act" like resistors in parallel..)

If Ι'm not wrong, 4μ7 is an input cap so you can try to use only one 2μ2 with some degree of "lows" attenuation..
(IMHO, 2μ2 with 2N3904 and 10k Collector resistor may sounds "better" - matter of taste, of course)

[Marcos - Munky]

The original schematic calls for 10uF at both input and output. But that really doesn't matter too much. I've built it so many times, using caps from 10nF (to use with a bass) to 10uF. One 2,2uF may sound good. Like Antonis said, it's a matter of taste.

But before tuning it into your tastes, we need to get it working first. Swap the transistor for any NPN. To my tastes, high gain ones, like an 2N5089 or BC549C (reverse pinout than the 2N) sounds better, but any NPN should work.

[mac]

If you are going to change transistors, then use a darlington, mpsa13 or similar.
Why? because this thing sounds better when the collector voltage is equal to the base voltage.

mac

[duck_arse]

I'd like to add - you can make your own discrete darlington from a pair of [insert low gain npn part number here] - just so's I can say @mac - that's a great new sig, going to confuse a few I bet.

[pinkjimiphoton]

i learned when building gus smalley's OUSB to ALWAYs ground pot casings. sometimes stuff won't work unless you do that... may stop passing signal, or may just squeal like a pig without proper grounding.

[antonis]

may just squeal like a pig without proper grounding.

Hey Jim..

What exactly is a proper grounding for a pig..?? 

[rankot]

 

[ilcaccillo]

please post the actual circuit diagram you are working from. you say "S8050" transistor, which is PNP on my datasheet, the usual bazz calls for npn.

The S8050 transistor is NPN and not PNP.
the PNP complimentary is the S8550

[ilcaccillo]

yes the s8050 is a pnp transistor it was labelled npn on the package and I didn't think to look up the data sheet... my bad