Small power supplies, do they exist?

[Zero999]

I'm guessing from the weight that they have a huge-ass transformer in them. Nobody makes those transformers cheaply any more. Not cheap enough to compete with the switch-modes anyway.

If you check on ebay you'll find plenty. Just look for a new (buy it now), variable, bench type power supply. Most of what you'll find under $100 will be cheap linear supplies with transformers.


http://www.ebay.com/sch/DC-Power-Supplies-/58288/i.html?LH_ItemCondition=1000&_nkw=variable+power+supply&_sop=15

I'd be tempted to buy one of those modules with an LED display, add a proper potentiometer with knob, put it in a nice case and power it from a switched mode 2A 24VDC wall wart.
http://www.ebay.com/itm/DC-DC-Blue-High-Efficiency-Variable-Power-Supply-Kit-With-Voltage-Display-2A-Out-/290866921083?hash=item43b904fe7b:g:d8sAAMXQhuVRJFpC

[MarkL]

Here's another for your consideration.  It's linear:

  http://www.mpja.com/0-18VDC-0-3-A-Variable-Benchtop-Power-Supply/productinfo/29600%20PS/

I've been tempted to pick one up, but haven't yet, so I can't vouch for the output or build quality.

They also have some switchers like this one:

  http://www.mpja.com/0-30VDC-0-3A-Variable-Benchtop-Power-Supply/productinfo/29616%20PS/

It has a fine adjust knob which is nice.  The ripple spec is not so great, but that's probably under full load, so it depends what you want to use it for.

They have a bunch in the tall style.  Here's the list:

  http://www.mpja.com/Benchtop-Power-Supplies/products/2/

[Fungus]

I'd be tempted to buy one of those modules with an LED display, add a proper potentiometer with knob, put it in a nice case and power it from a switched mode 2A 24VDC wall wart.
http://www.ebay.com/itm/DC-DC-Blue-High-Efficiency-Variable-Power-Supply-Kit-With-Voltage-Display-2A-Out-/290866921083?hash=item43b904fe7b:g:d8sAAMXQhuVRJFpC

Get one with volts/amps display and current limiting. They don't cost much more...

I've got one of these somewhere: http://www.ebay.com/itm/391036308115

It works well enough for that price. It would be a lot better with some proper pots on it instead of fiddly trimmers.

(Edit: In fact it costs half as much as the one you linked to    )

[klunkerbus]

Another thread recently mentioned the modules like this one.  Button control over both voltage setting and current limit, digital display selectable between voltage and current.

http://www.ebay.com/itm/Digital-controlled-Constant-Current-Voltage-DC-Step-Down-LED-Driver-Module-/151864371948?hash=item235bd26aec:g:150AAOSwl9BWL4Q6

This is a 3-amp one; there are others with different magnetics that can go up to 10 amps.

EDIT: Here's the other thread.  Post #33 includes a video review of the 40V 3A module.  Post 35 shows another module that would be more of a snap-in solution. https://www.eevblog.com/forum/beginners/what-do-you-think-about-these-very-inexpensive-benchtop-power-supplies/.

[Deckert]

blackdog built his own into a tiny cisco enclosure, schematics and everything available:
https://www.eevblog.com/forum/chat/show-your-favorite-and-mostly-used-benchtop-psu/msg194801/#msg194801

and there's this one in, what looks like, a 1U enclosure:
https://www.eevblog.com/forum/chat/show-your-favorite-and-mostly-used-benchtop-psu/msg223863/#msg223863

A number of other alternatives in that same (very nice) thread, started by BravoV.

--deckert