While waiting for the ordered parts, I made a 15V split power supply pcb:
http://musicfromouterspace.com/analogsynth_new/WALLWARTSUPPLY/wallwartbtmcopper.gif :
It needs an ac wall wart to power it. I have only one, that is for 12V. I was ready to order 15V one, but then thought: hold on, doesn't dc wall warts have already an ac output in them, that is rectified by using diodes to make dc voltage?
So I had to look, what I have in my boxes of 'stuff'. Surprisingly, there was 15V/500mA dc adapter, that didn't seem to belong to any device, that I use. I managed to open its enclosure, and took some measurements with multimeter. Yep, it could perhaps be used for the purpose.
Only two wires needed for straight ac output. Actually I'm going to use its dc wires for that, as they have a nice strain relief clamp already. No extra wires or holes needed.
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But there is one very serious precaution, though: to do something like that, one must be extra careful, as there is live 220V(in Europe) involved, when that adapter is connected to mains.
Disclaimer: If in any doubt, don't do it. If one still insist doing it, that one takes full responsibility, of what he's doing.
Only once I've had 220V shock, and yes, it was indeed very nasty, so I'll do my best to avoid messing with it.
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But enough of that. The 15V split psu will be a 'master' one, that feeds lower ones(like devices, that have 9V regulator in them). But we'll see, what comes out.
When looking inside of that previously mentioned ex-tape recorder enclosure, there was dust and a phase shifter:
I doubt, if it's still in working order, after two decades, due to corrosion of the pcb traces. As can be seen, two ic's are configured to substitute original op-amps(super-rare 4739's). White blocks are diy optoisolators(led/ldr), to replace original Clairex CLM6000's(that were probably never available outside US, but what do I know).
Quite a mess, that is worth only for looting socketed ic's, pots and switches.
I'm considering of rebuilding that, but what comes to optoisolators, they need some fiddling(when using ordinary leds and ldr's) to get them to the 'working range'.
Or just re-use the components inside white blocks, and look, what kind of mods I did use back then, to get them to work.