/diy/ - Do It Yourself

I want to make a 48V phantom power circuit for a BM-800 microphone, but I'm al little lost where to start. My circuit will use a balun of some kind since I'll be converting it for use with unbalanced 3.5mm audio (as opposed to just shorting one of the balanced ends to ground like some sort of troglodyte). Whether I use an actual magnetic core balun or a differential-amplifier solution is still to be decided.

I can't find any cheap 50V chinky AC-DC modules with the spelling I'm using, so I'm considering making my own. It doesn't need to be high-power. But I'd prefer a fairly simple topology, likely with a relatively clever control IC to keep switching noise down. Not sure how necessary isolation is, since referencing things to the neutral pin shouldn't cause any problems (I have polarised plugs here), but I'd rather reference them to ground instead since I have my grounded oscilloscope and function generator right next to where the microphone will go.
Anyone know what switching converters/controllers to go for that have 240V mains tolerance and bootstrapping ability? Preferably one I can buy on ali. All I can see at the moment are DK112s, which should have the punch required but rely on a bit of a shitty zener-diode feedback system, pic related. Not that it matters if I'll be using a linear regulation stage anyhow. The diode coming off the primary winding is also a bit strange looking. But they're cheap as chips, so I'll likely go for them.

My budget is ~$16, which is about what the existing phantom power supplies cost, but since they don't have the balun feature I'd be willing to go up to $20 I guess. Any tips?