THAT1512 / Transformer 'blind test' mic preamp

[DaveDC]

Not sure how your scope works but can it do a trigger view with the trigger source set to line? That might reveal your mains waveform safely. With no further clues, I suspect your mains is flat topped unless your transformer is saturating. It should not saturate with no load, I’d think. I could be wrong though.

 

[jamesk]

@DaveDC Yes, good idea, I'll do this when I get the chance, possibly tomorrow.

It's driving me a bit mad now because I can't see what's wrong with the design, it should work. I've built lots of linear power supplies before and never had so many problems. Anyway, it's the name of the game with DIY electronics!

 

[DaveDC]

You are using a proper scope probe, yes?