Noisy Power Supply Question

[jdduffield]

I have a fuzz face type of pedal that I build from a schematic using prototype board. I notice when I use one of my power supplies that has only 500mA, I get noise from the pedal’s output. (Almost sounds like night crickets in a forest.) But, when I use my other power supply that has 1700mA, the pedal sounds fine and is noise-free. Why is that? And is there something I can do within the build to ensure a noiseless power supply experience?

I know many pedals have a “clean power” section and never fully understood what that is all about, but wondering if this is the type of problem those power sections are resolving.

 

[JohnnyCreepy]

One thing I’ve picked reading this board and for you to try too is adding a 100nF cap (ceramic/plastic) from power jack socket positive connector to pedal housing with leads as short as possible. Best to ensure secure connection with bolt and lock washer. My OneSpot whines more than cheap Mr.Power one, but isolated Vitoos 12 (sold as fender engine room, behringer iso-12 etc.) is quiet even when powering digital and analog pedals with it.

Buildwise the placement of components on circuit and to each other, component lead lenght, wiring placement and orientation and quality of soldering give their effect to overall noise level with decisions on circuit topology and component choice. Not all components are equal (not even in the same batch) so compensation might be needed somewhere f.ex. on transistor biasing or IC slew rate adjustment. Tweak, adjust, tinker and lose your sleep! Maybe we could think populating a pcb with BOM components as navigation with GPS and you honestly don’t know if it misleads you without knowledge about the route. Then breadboarding could be thought as navigation with a map and compass, you’re free to choose how you get where you want and can make changes in the plan when needed to really get there.

Maybe something is misbiased or your beefier supply just has beefier AC filtering before transforming AC to DC. Dunno.

 

[jdduffield]

the placement of components on circuit and to each other, component lead lenght, wiring placement and orientation and quality of soldering

I built it on one of these. (See pic.) I wonder if these are known to be noisy. I used little jumper wires to connect columns together as needed.

 

[Nostradoomus]

protoboards aren't known for being super quiet, it's probably the differing supplies and who made them etc. Use the quiet one lol

 

[HamishR]

I once had a pedal which was fine when I played it at home but had that whine when I used a cheaper power supply in a music store. The trick in that case was to use the 1N5817 polarity diode. For whatever reason that cured the whine. Usually using the diode inline works, occasionally I need to add a 100R resistor in series too. Some power supplies aren't as well filtered as others I guess. It also seems that adaptors with transformers can be quieter than switching adaptors.

 

[jdduffield]

The trick in that case was to use the 1N5817 polarity diode.

New at this, but that would keep the voltage traveling in the right direction, correct?