25fbba02_rts_and_Sources___OpenCircuits__Comments
[What] Low Voltage Power Supplies [Where] Computers. Printers occasionally have nice, beefy, 20-40V, even AC psu's Christmas lights for 24VAC Obsolete cellphone chargers if you find a graveyard of them [Comments] 
Wall warts that may come with devices. Some other devices have power supplies as separate components. May want to supplement with a three terminal regulator, which you can also get from salvage.
Salvage Parts and Sources - OpenCircuits
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