Wall wart with dual output (ideally 12 and 5) (found one!)

[kristakis]

I'm thinking about a little project that'll use 12V and 5V and rather than a relatively large PSU brick or buck converter I was wondering if there were any wall wart style plug packs around that had dual outputs. I've seen multi-voltage single outputs and wonder if I could cheat something out of that with some diodes but before I go popping silicon in my room thought I'd check if anyone had seen anything like that around.

tia,
kris

edit: I forgot that USB-C allows for 12V and I found a plug pack with USB-A and USB-C outputs which will do nicely! I can't delete this post so I'll put this note here instead. I need a rubber ducky

[mariush]

The USB chargers don't output both 12v and 5v at the same time.  By default they output 5v and you can have a chip inside the product which negotiates with the charger and switches the voltage to other voltages like 12v.

There are power supplies that output 2 or more voltages but usually come with DIN connectors or other connectors (like miniature pci-e connectors, like the ones on video card)

But it will be easier to use a 12v only adapter with a barrel jack connector, and just add a 12v to 5v switching regulator inside the product, or a linear regulator if the current you need is very low on 5v.

[Haenk]

A lot of older HDD enclosures use a 5V/12V PSU (wall wart), using a Mini-DIN-Plug. They should be easy to source on ebay etc.

[NiHaoMike]

The USB chargers don't output both 12v and 5v at the same time.  By default they output 5v and you can have a chip inside the product which negotiates with the charger and switches the voltage to other voltages like 12v.

Could use one that has both a USB-C and USB-A output with the C set to 12V and the A used as is for 5V. Janky but those chargers are cheap enough nowadays. Of course, adding a buck converter for 5V is far more elegant.

[Alex Eisenhut]

Wall wart with dual DC outputs? Well, they existed... Very unusual even when they were still made
https://www.radwell.ca/en-CA/Buy/ELPAC/ELPAC/WM113/
But this might be a lead for more current parts

[amyk]

How much power do you need? You may be able to get by with a regular 12V supply and one of these, but ignore the 3.3V output on them: https://www.eevblog.com/forum/projects/pico-dcdc-12v-to-atx-160watt-at-1530-euro!/

[kristakis]

Could use one that has both a USB-C and USB-A output with the C set to 12V and the A used as is for 5V. Janky but those chargers are cheap enough nowadays. Of course, adding a buck converter for 5V is far more elegant.

That's what I'm thinking. The project has space restrictions and can fit 2 small PCBs rather than 1 large one - I had split the circuit to put the 12-5 buck converter on one board and the 5V circuits on the other with a small cable between them. But I thought if I could get both voltages from a plug pack rather than a mid-cable laptop brick that would mean I could get away with 1 PCB even if it ends up with 2 USB sockets on it.

Two USB cables, likely cable-tied togther, will not be pretty but this will be inside a vending machine and not visible. Also I hoped that a reduced complexity in the PCB and increase in user-replaceable parts would make non-technical servicing easier too.

Thanks everyone for the links.