[sdiy] Help trouble shooting noisy circuit

[Oren Leavitt]

I wonder if that TL072 is driving dirty or aging components? Those could 
be placing increased capacitive loading on it and causing it to 
ring/oscillate. TL07x is sensitive to that. Try something like a 1458 
and see if the self-oscillation stops.

Another possibility could be residues on the photo etched board that 
have caused some degradation over time.

A couple guesses..

A schematic of the circuit would help us troubleshoot.

- Oren

On 1/12/25 5:03 PM, Joe Frey wrote:
> Hello, more than a decade ago I built with Harry Bissell's help a pitch
> to voltage circuit and an envelope follower and then built some
> supporting boards: power supply and two invert-offset circuits. One of
> the invert-offset boards is not functioning properly. It is a photo
> etched circuit board unlike it's brother that was made on strip-board.
> The invert and offset functions work properly but the output has a high
> frequency wave in it whether there is an input voltage or not. The
> brother circuit on strip-board works fine. Same power source for both. I
> have checked the component values(there are only resistors), checked all
> the traces with the circuit on paper, re-flowed all the solder joints
> and replaced the TL072  with others. I still have the issue. What should
> I look at next?
> 
> Is it possible that a faulty IC socket could produce this effect? I
> didn't change the socket because this basement darkroom circuit board I
> made then seems pretty fragile.
> 
> Thanks for any help. JoeF.
> 
> 
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org
> View archive at: https://synth-diy.org/pipermail/synth-diy/
> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org