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Biggles · 8th Sep 2019, 10:30 am

That definitely sounds like oscillation/instability to me. Does it all quieten down and behave with the preset refitted? Could just be poor pcb design. Personally I have never had a problem with using linear regulators, even when constructed with veroboard. I do always use the decoupling on input and outputs though, maybe 0.1 and something like a 10 microfarad in parallel?
Alan.

8th Sep 2019, 10:30 am	#25
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Defective/ fake LM317T That definitely sounds like oscillation/instability to me. Does it all quieten down and behave with the preset refitted? Could just be poor pcb design. Personally I have never had a problem with using linear regulators, even when constructed with veroboard. I do always use the decoupling on input and outputs though, maybe 0.1 and something like a 10 microfarad in parallel? Alan.