I was just watching a Great Scott! video*, got reminded of frustration I had recently when wanting to use op amps alongside a microcontroller. A few years ago I'd have started with a split-rail supply with linear regulators suitable for the op amps and used a 7805 or whatever to drop to logic chip levels. But nowadays the mcu takes centre-stage (and there is a convenient power source over USB).
I wanted to power an ESP32 plus an ADC plus a bunch of analog gain/filter stages, audio frequency from USB or worst case a 9v wall wart. I have accumulated a drawer full of little buck/boost converters, but no combination of what I had gave an nice solution. Ended up boosting to around 28v, then using a resistor divider for 0v. Inelegant and adding a complication. I've had stability issues in the past getting a 0v this way, case grounding and suchlike can also be an issue.
I've only skimmed the catalogues but the only suitable modules available seemed to have a ridiculous dollar price compared to single-rail designs.
So here's the challenge : using standard inexpensive components, design a circuit that would take say 5-12v as input (ideally also from 3.3v if viable without too much extra effort) and give +/-12v ... +/-15v output. Not much current needed, say 100mA (though more would be nice to have). Requires good stability & reasonably low noise (random or switching) in the audio range. High efficiency not a priority, but obviously nice to have.
Maybe there's a good solution I'm not aware of, but nothing sprang out. The irritation factor is such that I'll no doubt have a go myself (even though I've little experience in this corner), but I thought it'd be be good to put here as a fun design challenge, see how folks might approach it. Is far from niche - data acquisition, signal generation, lots of audio/music stuff. While audio freq analog processing can be done with single-rail op amps etc, it usually comes at a cost somewhere else in the specs (or price).
Cheers,
Danny.
http://hyperdata.it*