Where do people get the PSU for their projects ??

[MathWizard]

Pretty much all the little projects I've made, that needed their own PSU section, I just used salvaged circuits and PSU's re-purposed from say stereo's and wall chargers.

And I've always been too cheap to order a transformer of any type, either linear or for switching, and they are at the heart of most any PSU section.

So what does everyone else do ? Do you re-use old junk like I do, or order a transformer and make your own? Or do you buy a pre-built PSU in a box ??

[ftg]

I either reuse junk, re-use some iron transformer from my junkbox, buy a MeanWell from TME.eu or just give the device USB-C.

[madires]

For projects which can be powered externally I go for common 5 or 12 V wallwarts (USB, barrel connector) and add a buck converter or linear regulator. If an internal linear PSU is needed, e.g. classic audio amp, I first check if I already have a suitable transformer, otherwise I'll buy one.

[themadhippy]

Do you re-use old junk like I do, or order a transformer and make your own? Or do you buy a pre-built PSU in a box ??

yes. It all depends on the project.

[rteodor]

Yep, it depends a lot on the project. When doing multiple boards I like to use these AC/DC modules. Just about any variant from 3.3V to 24V.

[rvalente]

Brick modules are also quite common as well.

https://www.hlktech.net/index.php?id=product&cate=cate703

[Driftless Engineering]

A wall-wart with a barrel connector is super easy if you aren't the type to lose the right cable for your project.

Most of the small things that only need 1-2 W I'll power at 5V with a USB cable, because I'm more likely to have a spare USB brick and cable than the barrel connector I need.

If you like a more finished product, I like to buy an AC/DC Converter from someone like TDK Lambda, along with a power entry module and cabling. That way I can just use standard C13 power cable you'd use for a PC.

You can find all of this stuff on sites like digikey.com and mouser.com.

[Doctorandus_P]

I've got a big bunch of laminated iron core transformers scavenged from long ago, and I sometimes use them for my own projects. But if I don't have a "fitting" transformer then I just buy whatever power supply is appropriate for the project.

I also dislike messing around with mains voltage for all the small projects. So I've put a 24Vdc power supply somewhere in a corner and made a home network that uses 24Vdc and Uart/RS485 for communication over CAT-5 cable. Each node has it's own small buck converter.

[NiHaoMike]

There's often high power PSU modules available for reasonably cheap on Ebay, particularly 12V and to a lesser extent, 48V. Those server PSUs and telecom rectifiers are built very well and even the used ones will last plenty long for hobbyist applications.

For low powered stuff, salvaged wall warts and USB inputs are often the way to go.

[Benta]

I used to do all of the above, but after the relatively new EU regulations on wall-warts, I'm gloriously happy. Best thing the EU ever did.
USB-C wall-warts are available OTS as 15...65 W types, and even up to 240 W as PD 3.1.
Why bother with PSU design? USB-C is compact, easy, small connectors etc. And with mass production cheaper than anything you can make yourself.
Forget barrel connectors, there must be at least 50 permutations, so you'll never have the right one.
Done deal.

[SteveThackery]

I used to do all of the above, but after the relatively new EU regulations on wall-warts, I'm gloriously happy. Best thing the EU ever did.
USB-C wall-warts are available OTS as 15...65 W types, and even up to 240 W as PD 3.1.

How easy is it to persuade these USB-C wall-warts to deliver those high powers? Isn't there some complicated negotiation required?

[ftg]

There is, but one can buy ready made "USB-C trigger" boards that do that for you.
Or use something like CH224.
3A 20V is 60W and 5A 20V is 100W, and that's plenty for many applications.
I have powered some nominally 13.8V radios with 15V sourced from phone chargers.

[rteodor]

There is, but one can buy ready made "USB-C trigger" boards that do that for you.
Or use something like CH224.

Sounds complicated. How much would it cost usually ?
Like the white PSU above 60W/24V was about 15 EUR. Simple and very compact with IP67.

[Benta]

Sounds complicated. How much would it cost usually ?
Like the white PSU above 60W/24V was about 15 EUR. Simple and very compact with IP67.

There are plenty of ICs out there that will do the job. As an example: ST STUSB4500. Will handle up to 20 V, 5 A. US$ 1.80 per 100 pcs.

[0100010]

I must be old.  I find I much prefer old school linear power supplies, in all their hot, inefficient, low ripple gloriousness.

[bson]

A USB C connector and a pair of 5.1k CC resistors covers practically all projects for me, combined with a 3.3V buck converter.

If I needed more I'd probably just find a suitable Mean Well or something.

[Konkedout]

I have a bunch of 18V-20V laptop power adapters laying around.  These are inexpensive in $/watt.  I prefer the barrel connectors, but when I want to use them for my own purposes I will generally cut that off.

1) I connect the power adapter to my board using a terminal block.   By itself this does not protect against reverse polarity, so......
2) I will pass the power through a rectifier diode to protect against that.  If I do not want to suffer the 400 mV drop or so from a Schottky rectifier, I will also connect an appropriate MOSFET as a synchronous rectifier.  Source to + input and drain to output.  My projects will usually contain a switching regulator, so I AC couple some high frequency into a charge pump to charge up the gate of that MOSFET.  This works well.

I have a great supply of (the diodes and MOSFETs for example) from previous jobs, so this works for me.

I do not like USB-C (or Thunderbolt) connectors because those seem too petite and flimsy.   My Rigol oscilloscope is powered by an external USB-C power supply, and that is one aspect about it that I dislike.  USB-C is good for a smartphone but not for my lab project.   Also I do not want to bother with that voltage negotiating illogic.

[Andy Chee]

I must be old.  I find I much prefer old school linear power supplies, in all their hot, inefficient, low ripple gloriousness.

Linear power supplies are mostly obsolete in modern equipment.  So where do you obtain extra linear supplies for your new electronic projects?  Do you have a stockpile?  Or maybe you don't build much, thus your availability of linear power supplies will last you for a while?

FWIW, my go to supply are 19V laptop power bricks.

[ftg]

There is, but one can buy ready made "USB-C trigger" boards that do that for you.
Or use something like CH224.

Sounds complicated. How much would it cost usually ?
Like the white PSU above 60W/24V was about 15 EUR. Simple and very compact with IP67.

I think I paid less than 1eur/pcs for the USB-C trigger boards I have in stock.
They might be more expensive now.
With those I can use whatever USB-C power supply I have and get more than 5V from them.

[coromonadalix]

I must be old.  I find I much prefer old school linear power supplies, in all their hot, inefficient, low ripple gloriousness.

Linear power supplies are mostly obsolete in modern equipment.  So where do you obtain extra linear supplies for your new electronic projects?  Do you have a stockpile?  Or maybe you don't build much, thus your availability of linear power supplies will last you for a while?

FWIW, my go to supply are 19V laptop power bricks.

oh contraire 

linear are still up to the game,  smps, phase controlled or other technologies are good too,  depends of your needs,   
some do not handle  capacitive or inductive loads and can or could blow up,  even a cheap short circuit can play some trick, or overloads (response times)

[themadhippy]

So where do you obtain extra linear supplies for your new electronic projects?  Do you have a stockpile?  Or maybe you don't build much, thus your availability of linear power supplies will last you for a while?

build em,all the bits are available off the shelf at your local parts empourium

[Solder_Junkie]

Be careful with linear supplies, if the pass transistor(s) fail you end up letting the smoke out of your project. Switch mode supplies are generally "fail safe" but for expensive equipment I still use an over Voltage protection board using an LTC-4368 and a power MOSFET, details attached for those interested.

I have a few surplus switching supplies that have originally been phone chargers (pre the USB-C days) and some 12V and 15V laptop supplies with barrel connectors that are easy to change.

SJ

[MariuszD]

For debugging, I use linear power supplies with adjustable voltage and current limiting. For powering finished circuits I use wall-wart or laptop power supplies.
From second-hand sources, they are very cheap, so I wouldn't bother making one.

The last linear power supply designed for integration into a device I built had an overheating transformer, even though the load was small. The manufacturer of this transformer was once considered a good brand, but as the market began to shrink, the quality of the products deteriorated.