Small power supplies, do they exist? - Page 1
Forum section: electronics / testgear

author: SharpEars
author_rank: Unknown
timestamp: November 24, 2015, 03:03:27 pm
content: It seems like any variable voltage/variable current power supply these days is very wide, very deep, very heavy and very loud.Aren't there any small adjustable voltage/current supplies with passive cooling that provide a meager voltage/current output but also use very little desk space. I am looking for a small one that I can put on my computer desk. 0-10 V is fine and I don't need more than 250 mA, although more would be welcome if it comes in a small package.With all of the switching regulators available these days, it's hard to believe no manufacturer has created a boxed up unit that is small and light. I mean seriously, I could stock up on a buck converter and a panel meter and build a tiny variable supply powered by a wall wart that takes almost no desk space. There has to be something already pre-fabbed that meets this description - I can't believe I am the first person to think of this.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 03:08:37 pm
content: http://www.ebay.com/sch/i.html?_nkw=CPS-3205

author: SharpEars
author_rank: Unknown
timestamp: November 24, 2015, 03:10:09 pm
content: Quote from: Fungus on November 24, 2015, 03:08:37 pmSmaller! ..., and with front outputs for convenience.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 03:21:41 pm
content: Quote from: SharpEars on November 24, 2015, 03:10:09 pmI guess there's no pleasing some people!http://www.ebay.com/itm/141812241288

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 24, 2015, 03:26:37 pm
content: Quote from: SharpEars on November 24, 2015, 03:03:27 pmMost people like big testgear (to a certain point). I know I do (and have friends that do to) because bigger gear (usualy) has bigger screens and buttons to mash.And most of them aren't exactly load... The high power ones are, and often the tiny ones are too because they don't have room for the big heatsinks, being tiny and all) and need whiny (smaller fans tend to whine harder due to turbulence magic afaik) fans.If the one in the ebay link is already too small... I think you are better of building your own

author: SharpEars
author_rank: Unknown
timestamp: November 24, 2015, 03:46:22 pm
content: Quote from: Fungus on November 24, 2015, 03:21:41 pmWell, that is smaller! But where is the nice voltage/current display and current adjustment knob, not to mention case.

author: dom0
author_rank: Super Contributor
timestamp: November 24, 2015, 04:03:26 pm
content: Philips made a series of cutie supplies. E.g. PE 1509 (30 V / 400 mA). They all have the same case, about 70 mm wide, maybe 120 mm tall and at most 200 mm deep.HP made many similarly small power supplies with almost any combination of voltage / current up to a few hundred volts. The smallest ones have ~10 W output power and are so small, that there weren't really space for a IEC plug at the rear; the mains cable is fixed...They also made some in the system 2(?) case (think HP 3400A), e.g. the 6226A/B.Other P/Ns:721A6234A, 6235A6216A, 6217A, 6218Aand many moreThere are many Chinese models of "slim line lab supplies" available, but I think most are switchers, so not really an option...

author: xtech
author_rank: Regular Contributor
timestamp: November 24, 2015, 04:06:28 pm
content: Maybe BK Instruments 1550? I have it - UI is little bit stupid (rotary encoders instead buttons, current limit can be read only with shorted outputs) but it is small and very light (it is switching mode supply). And what is most important there are no voltage peaks when load is rapidly changing.

author: Marco
author_rank: Super Contributor
timestamp: November 24, 2015, 04:18:54 pm
content: Quote from: dom0 on November 24, 2015, 04:03:26 pmIf they have post regulators I don't see why not. I have homeplug on my mains, my linear power supply isn't getting anything cleaner to work with than a switcher post regulator.

author: rgawron
author_rank: Contributor
timestamp: November 24, 2015, 04:24:00 pm
content: http://www.tme.eu/en/details/nsp-3630/one-channel-power-supplies/manson/Pluses:-small-lightweight (2kg), easy to grab and move by using a single hand-no fan (noiseless)-solid metal chassis-big display, easy to read from various angles-quite cheap, around 130$Minuses:-one channel only-output voltage is relatively noisy-no USB/LAN connectionI have one and I'm happy with it.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 04:28:39 pm
content: Quote from: SharpEars on November 24, 2015, 03:46:22 pmDo I have to doeverythingaround here?http://www.ebay.com/itm/181863444001http://www.ebay.com/itm/400982197535http://www.ebay.com/itm/151876252952

author: Cubdriver
author_rank: Unknown
timestamp: November 24, 2015, 04:32:15 pm
content: With some patience, these small HPs can be found on the 'bay, typically (again with some patience) in the $30-$60 range. They're 5-1/4"w x 8"d x 3-1/4"h (133 x 368 x 83mm), and weigh about 4-1/2 lb each.The 6216A is 0-25V @ 0-400mA; the 6218A is 0-50V @ 0-200mA; and the 6212A is 0-100V @ 0-100mA. There is also a 0-10V one, but I don't have one of those. All are constant voltage/constant current supplies, with coarse and fine adjustments for each. The downside is that with only 1 meter (switchable), you can only read one parameter at a time. Other than that. they're solid, silent little buggers.-Pat

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 04:44:57 pm
content: Quote from: Cubdriver on November 24, 2015, 04:32:15 pmCutelooks like the ones we used at school....but much bigger then the one I posted, which was still far too big for Mr. Fussy-Pants OP...and if something the size of a paperback book is too big, then...

author: tautech
author_rank: Super Contributor
timestamp: November 24, 2015, 05:59:33 pm
content: These are my favourite:https://www.eevblog.com/forum/testgear/cheap-variable-switching-power-supply/You just can't break them.

author: Cubdriver
author_rank: Unknown
timestamp: November 24, 2015, 06:11:09 pm
content: Quote from: Fungus on November 24, 2015, 04:44:57 pmI like 'em (obviously, looking at the pile of them) - they're small, quiet, have current limit and stack. Not to mention well made.-Pat

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 06:33:44 pm
content: Quote from: Cubdriver on November 24, 2015, 06:11:09 pmI can tell.The only thing that worries me is the accuracy of the voltage display/setting. It doesn't look easy to dial exactly (eg.) 3.3V without using an external multimeter.Edit: I just noticed they aren't all the same. There's one that only goes to 30V on the scale, that one might not be too bad.There's a few on eBay right now for about $60 but shipping something that heavy to Spain would destroy me.Quote from: Cubdriver on November 24, 2015, 06:11:09 pmMine, too.

author: rdl
author_rank: Super Contributor
timestamp: November 24, 2015, 06:39:52 pm
content: Quote from: Cubdriver on November 24, 2015, 06:11:09 pmKind of makes you wonder why someone hasn't made a knock off of these, instead of building the same old junk over and over like they do.

author: nctnico
author_rank: Super Contributor
timestamp: November 24, 2015, 06:41:05 pm
content: Quote from: dom0 on November 24, 2015, 04:03:26 pmWhy not? HP has many lab switchers which pack a big punch in a relatively small and lightweight box. Small Chinese ones can be found but may be less well filtered so less suitable for very sensitive circuits but perfectly suitable for powering many other devices.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 06:48:51 pm
content: Quote from: rdl on November 24, 2015, 06:39:52 pmI'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.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 06:52:30 pm
content: Quote from: tautech on November 24, 2015, 05:59:33 pmDo they have an output enable switch or just a big honking on/off button?(I mean, can you see the displays and make adjustments then they're "off"?)

author: tautech
author_rank: Super Contributor
timestamp: November 24, 2015, 06:56:52 pm
content: Quote from: Fungus on November 24, 2015, 06:52:30 pmNo.Read the thread.....NO over or undershoot.Ask nctnico, he got one based on what he read in the thread.I'll say this; for all low current use at any voltage, the fan will never turn on.

author: nctnico
author_rank: Super Contributor
timestamp: November 24, 2015, 06:58:13 pm
content: Quote from: Fungus on November 24, 2015, 06:52:30 pmBe sure to read the entire thread because these small PSUs certainly have issues (including ones with safety). I wouldn't recommend them unless they are rebuild properly to good safety standards.

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 07:01:52 pm
content: Quote from: tautech on November 24, 2015, 06:56:52 pmBummer.Still, I guess it's easy enough to put a switch in your wires. Just nice to have one on the PSU though.Quote from: tautech on November 24, 2015, 06:56:52 pmThat wasn't the question

author: rdl
author_rank: Super Contributor
timestamp: November 24, 2015, 07:03:40 pm
content: Quote from: Fungus on November 24, 2015, 06:48:51 pmIf 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

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 07:09:54 pm
content: Quote from: nctnico on November 24, 2015, 06:58:13 pmLooks like there's dozens of manufacturers as well. That's never good when buying Chinese products - you don't know what you're getting.

author: Zero999
author_rank: Super Contributor
timestamp: November 24, 2015, 07:27:09 pm
content: Quote from: rdl on November 24, 2015, 07:03:40 pmI'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

author: MarkL
author_rank: Unknown
timestamp: November 24, 2015, 07:55:14 pm
content: 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/

author: Fungus
author_rank: Super Contributor
timestamp: November 24, 2015, 08:36:34 pm
content: Quote from: rdl on November 24, 2015, 07:03:40 pmGet 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/391036308115It 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)

author: klunkerbus
author_rank: Unknown
timestamp: November 24, 2015, 08:50:05 pm
content: 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:150AAOSwl9BWL4Q6This 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/.

author: Deckert
author_rank: Regular Contributor
timestamp: November 24, 2015, 09:33:38 pm
content: 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/#msg194801and 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/#msg223863A number of other alternatives in that same (very nice) thread, started by BravoV.--deckert