Basic audio scarab deluxe noise

[Lost_soul]

I made a basic audio scarab deluxe based on this layout:


And i think this is the Schematic


So the problem is that when the pedal is working there is high noise. When adjusting the fat control below maximum it starts picking up radio sounds. When the bias knob is below max it introduces more noise until it reaches say 10 o'clock then it becomes gated fuzz like.

I made all the connection with alligator clips for testing. I used a 9v battery too.

Here is a sound Sample

And here are some pics:





Could this be just how the pedal is and maybe when i box it, it will be solved? Idk

Btw i used 2N3904 for all transistors and i used 20k for the bias pot instead of 25k.

[antonis]

Noisy unboxed Fuzz..??
There shouldn't be such a thing..!! 

When adjusting the fat control below maximum it starts picking up radio sounds.

Place a 1nF cap between Q1 Base and Emitter..

P.S.
I know it should upset your layout but it should be prudent to transfer +9V on Q4 Collector and populate a couple of RC LPFs in between stages..

[Lost_soul]

Noisy unboxed Fuzz..??
There shouldn't be such a thing..!! 

I don't know if you are being serious or joking

I will place the capacitor and see how it goes.

As for the modifications, maybe i will look into them in another one i make. But as for now it's gonna be hard to make them on the existing build

What about the bias pot? On max no problem, on minimum no problem, but from 9 to 3 it raises the noise.

[Lost_soul]

Noisy unboxed Fuzz..??
There shouldn't be such a thing..!! 

I don't know if you are being serious or joking

I will place the capacitor and see how it goes.

As for the modifications, maybe i will look into them in another one i make. But as for now it's gonna be hard to make them on the existing build

What about the bias pot? On max no problem, on minimum no problem, but from 9 to 3 it raises the noise.

[R.G.]

Noisy unboxed Fuzz..??
There shouldn't be such a thing..!! 

I don't know if you are being serious or joking

He's serious-joking. A fuzz is a high gain device, and the vast majority pick up noise and RF when not inside a grounded metal box. Yeah - the problem might vanish when you put it inside a metal box.

What about the bias pot? On max no problem, on minimum no problem, but from 9 to 3 it raises the noise.

You're dealing with radio frequency (RF) issues. RF is not confined to wires very well, and conversely, the inductance (that is, length and bend/coil) of wires and capacitance (to any nearby conductor) matter. The wires to pots can literally be both an antenna and an RF resonator. This might be fixed by a shield box, or it may require RF-proofing caps and such inside the circuit as well.

Pots have a quirk. They have their highest source impedance in the middle of their range, where the resistance to both ends is highest. It is likely that the middle-of-range in the bias pot is causing some gain condition to hit critical values to make wiring tuning pull in RF.

I like Antonis' decoupling setup, as it removes feedback through the power wiring, but I would add a 0.01 to 0.1uf ceramic cap in parallel, or in place of those 100uf caps. Electro caps are good for many things, but they're not great at shunting RF to ground.

[Lost_soul]

He's serious-joking. A fuzz is a high gain device, and the vast majority pick up noise and RF when not inside a grounded metal box. Yeah - the problem might vanish when you put it inside a metal box.

Antonis is the JOKER 

i understand now. I was so amazed when it picked up my radio signal!

So what should i do? Should i just ignore it until i box it or should i add a 1nf between Q1 base and emitter. Or should i add 100nf (or. 10nf) ceramic caps on where i marked with red in the picture?