Green Ringer hums

[ugly_guitar_guy]

I finished up my Green Ringer clone in a 1590A, and for some reason the damn thing makes what sounds like a ground hum if I use a power supply, but not if I use a battery (I make little 9v clip to dc plug pigtails for testing). Anyone have an experience like this or some direction where to start looking to remedy the problem?

[Mark Hammer]

It suggests to me that either:
a) your power supply is insufficiently regulated
b) you culd use a filter cap on the supply line in the pedal
c) both

[ugly_guitar_guy]

It suggests to me that either:
a) your power supply is insufficiently regulated
b) you culd use a filter cap on the supply line in the pedal
c) both

I'm using a BOSS PSA-120S power supply that I've never had any issues with on any of my other builds, and I don't have hum using it with other pedals still, so I don't think that could be the issue.

This is the layout I used:



Isn't C2 the power filter cap?

[Mark Hammer]

C2 is that very cap.  Is the + side up where the V+ connection is?  If not, then you aren't getting any filtering.

[PRR]

> I don't have hum using it with other pedals

R2 R3 pass 25% of any small power ripple into the input at Q1 and there is substantial gain from there to the output. It may be more sensitive to power quality than many other pedals. (The fact you need an adapter also suggests it was only intended for pure clean buzz-free battery use.)

The fast/simple fix is to bring the power in via a 100 ohm resistor so that the 100uFd C2 has some leverage against the power supply ripple. While you are moving the +9V red wire, I like it better "away" from the input end; this also makes a handy place to cut a strip and insert the 100 ohm resistor.

[ugly_guitar_guy]

Sorry for the delayed response, but I just pulled the pedal back out this week and added the 100R resistor tonight, AAAAAAAAAND...

No more hum!!

Thanks for the help PRR! My 1590A Green Ringer (aka "Ugly Frog") lives!