jdduffield
Active member
Hi,
I’m trying to figure out what type of noise this is so that I can try to fix it. Does anyone recognize what this is?
See video:
Maybe DC voltage getting on it, or maybe high frequency oscillation? I don’t know enough about what I’m listening for to diagnose.
This is a design I came up with that works on a breadboard. See schematic attached. I’m trying to install it into a pedal.
I’ve ruled out a few things. The op amp is fine. I’ve tried swapping it and no luck.
It is a TL072. Using two non-inverting gain stages. First stage is fine (using pin 3, 2, and 1). Stage 2 has problems. Pin 5 sounds good. 6 sounds good. But 7, the output, sounds bad.
I’m getting 4.5v on vref, so my voltage divider is working.
Tried a few things, like adding a 47p cap across pin 6 and 7. Didn’t help. Seems all is well until the circuit gets to pin 7.
Btw - pin 8 has +9v as suggested by the schematic. Pin 4 is grounded.
I’m trying to figure out what type of noise this is so that I can try to fix it. Does anyone recognize what this is?
See video:
Maybe DC voltage getting on it, or maybe high frequency oscillation? I don’t know enough about what I’m listening for to diagnose.
This is a design I came up with that works on a breadboard. See schematic attached. I’m trying to install it into a pedal.
I’ve ruled out a few things. The op amp is fine. I’ve tried swapping it and no luck.
It is a TL072. Using two non-inverting gain stages. First stage is fine (using pin 3, 2, and 1). Stage 2 has problems. Pin 5 sounds good. 6 sounds good. But 7, the output, sounds bad.
I’m getting 4.5v on vref, so my voltage divider is working.
Tried a few things, like adding a 47p cap across pin 6 and 7. Didn’t help. Seems all is well until the circuit gets to pin 7.
Btw - pin 8 has +9v as suggested by the schematic. Pin 4 is grounded.
