Just reading through some new design notes last night and came across Linear Technology Design Note 559.
This is a nice layout as there is no optocoupler but still fully isolated and it's very simple. Easy to make on-line too, by just rectifying the mains in (like a lot of SMPS solutions) so wouldn't matter if mains was 115V or 230V or 250VAC
Using a sensing winding (not a new idea) means there is nothing in the secondary to impact anything audibly, whilst still giving rock-solid regulation in a small size.
For a small headphone amp or something where you didn't want a lump of iron... pretty low switching speeds (in the 3-50kHz range), so layout important too... (as it always is with an SMPS)
Pretty much any secondary voltage you want pretty easily... (or even multiples, e.g. Vh and B+)
Just a thought.
Interesting non-intrusive HT/B+ SMPS idea
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#1 Interesting non-intrusive HT/B+ SMPS idea
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