Radio noise

[Lbzg]

Hi,

What causes radio interference when engaging a pedal?

I have build tufnel distorsion from Beavis but with A10K pot instead of B10K pot. Can this cause that radio signal coming trough the amp?

How to remove that radio interference? What can be wrong with pedal?

[R O Tiree]

Try something like a 47pF or 100pF cap from Input to GND. You will not lose any of your Input signal at audio frequencies, but it will shunt radio frequencies straight to GND before they get to the gain stage of the circuit.

The different pot type (A vs B) will not cause this.

Cheers

[Lbzg]

Thanks. Will try that and report back. By input to ground you mean on board right? Not on input jack...

And one quick question...can 10ohm resistor that is on 9Vin be replaced with 100k because it gets pretty warm when pluged into power supply...do I need to use higher or lower resistors to keep circuit cooled...do not wonna burn my components...

[armdnrdy]

Didn't Nigel Tufnel have radio interference coming through his amp?

Maybe this is part of the "Tufnel" signature sound!

Some people would pay extra for this! 

[rousejeremy]

Shielded cable on the inputs is a good idea to minimize RF interference as well. And keep the wires as short as possible.

[R O Tiree]

Thanks. Will try that and report back. By input to ground you mean on board right? Not on input jack...

And one quick question...can 10ohm resistor that is on 9Vin be replaced with 100k because it gets pretty warm when pluged into power supply...do I need to use higher or lower resistors to keep circuit cooled...do not wonna burn my components...

Yes, on the board.

As to the 10 ohm resistor... It should be 100 ohms, not 10, at least according to the schematic at Beavis Audio. That will run a lot cooler. If you use 100k, then the circuit will get almost no voltage across it and things will get awfully quiet... 100 ohms FTW.

[Lbzg]

Thanks man! That 100pf helped! Radio interference is gone!

Yep I misspell 100ohm resistor...I putted 100ohm and added a 1K to it but still it is getting hot...can it be that I have put components to close to each other? I have only one hole in between them...   

[R O Tiree]

I'm glad the radio interference is gone

Now, I do not think that this circuit should draw enough current to make that 100 ohm resistor too hot. There may be something else wrong. Feel the ICs... are they hot as well?

Cheers.

[Lbzg]

I have repaired it! It was lack of space. I replaced it little further on board and heat was gone. :-)

Also I noticed that B1K cannot be wound all the way up coz they produce high pitch noise then...I don't know is that good or not or what can it be...they both act like that...and also when I put power supply in I hear loud background noise all the time...

[ch1naski]

Try separating the input/output wires, and shielding them. High gain circuits tend to squeal when i/o wires cross and they are not shielded.