Make your own regulated power supply
Make your own voltage regulated power supply with spare parts. With old transformers or/and some cheap of the shelf Ali Express voltage regulators and build in voltage and amperage meters.
Beautifull stuff if you like to build circuits and often need a different DC voltage.
I use my build in the first project to create colloidal copper.
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https://www.paypal.me/emc4u2
Cheers,
René