It's not terribly difficult to build a Power-Supply that will last over ~100-years,
"The-Devil-is-in-the Details" always applies.

One of the larger expenses will be the Transformer, or SMPS used.
The SMPS will require much more careful Filtering-Measures to insure that it's "Electrically-Quiet",
in any case, 300-Watts is not a trivial undertaking.

HEAT is the next issue,
a fully PWM regulated Supply will generate the least waste-Heat, but is more difficult ( expensive ) to build.
A Transformer with a multiple-Tapped-Secondary will reduce the Heat-losses substantially,
but will require a substantial Heat-Sink and Fans in any case.

Do You want a "Sticks-and-Rocks", simple project ?,
or a much more sophisticated and complex project ?,
either can be designed to provide comparable Output-Performance.
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@LowQCab

It has become quite obvious that I need to consider building at least one psu.

Then there is the need for same to drive the projects once they're completed.

So for first run - - - quantity one for use in building and testing (that means that I need something like 30V and 3A).
Projects - - - well there is quantity 12 and dunno if that's going to be 5V but there is need for one 24V in that mix as well.

I went looking on here for similar - - - I really don't know how to determine which is a well done version or not.

So I'm looking for a more sophisticated (and more complex) power supply rated at 30V and 3A.

TIA

 

Your specifications are not cheap.
Do You really need ~30-Volts ?, ( plus and minus ~15-Volts ) ?
24-Volts will probably handle everything you'll ever need, and is less expensive.
2 used ATX Power-Supplies will provide 24-Volts when wired in series.

A Current-Limiting adjustment is nice to have, but Fuses will also protect against Shorts.

This Video may give You some ideas ..........
.

 

Seeing as how I have a few of these laying around, and expect to get one or two more soon, I'd recommend looking for an old ATX computer power supply. They don't run higher than 12 volts but maybe they can be modified. I wouldn't recommend that though. Messing with these things can be problematic.

Anyway, here's a link to turning an ATX power supply into a bench supply.

Would make a fairly nice project. Just work safe. Make sure the power is unplugged and the caps have had a chance to dissipate their charge.

Your specifications are not cheap.
Do You really need ~30-Volts ?, ( plus and minus ~15-Volts ) ?
24-Volts will probably handle everything you'll ever need, and is less expensive.
2 used ATX Power-Supplies will provide 24-Volts when wired in series.

A Current-Limiting adjustment is nice to have, but Fuses will also protect against Shorts.

This Video may give You some ideas ..........
.

? Same video ? Don't know about you @ThePanMan this sort of thing bugs me.

 

Yes, it bothers me too. Thanks @Tonyr1084.

 

2 used ATX Power-Supplies will provide 24-Volts when wired in series.

Never thought of that. One thing crosses my mind - grounding. Wouldn't grounding negate the ability to series the supplies? Unless you disconnect the grounds internally from the mains ground. Will have to think on that one a bit.

OK, going to the reading room. Be back later.

And Happy New Year Y'all.

 

Your specifications are not cheap.
Do You really need ~30-Volts ?, ( plus and minus ~15-Volts ) ?
24-Volts will probably handle everything you'll ever need, and is less expensive.
2 used ATX Power-Supplies will provide 24-Volts when wired in series.

A Current-Limiting adjustment is nice to have, but Fuses will also protect against Shorts.

This Video may give You some ideas ..........
.

Thank you for the info.

Pulsator coil that I want to drive is rated at 260 mA @ 24V or 540 mA @ 12V.
I'm assuming that that means 0 - 24V not -12 to 12V but I cannot find more information or better information. (The large corps want me to purchase their c**p(!) not try to roll my own.)
The idea of 2 ATX power supplies in intriguing - - - am thinking maybe using a buck/boost circuit on a 19V (65W) laptop power supply.
You've been quite helpful - - - - what is the recommended procedure for when one has some dozen either micro-controller or SoC micro-computer that need powering. These will be run within a 5 m (15') span. Preference to a ps for each node or one for the lot.
(Items will be pretty much running at similar times although not necessarily exactly at the same time.)

TIa

 

"" micro-controller or SoC micro-computer ""
These are very low Current devices by themselves,
but what they are controlling may need significant Power.

2 Laptop SMPSs from your local Computer-Repair-Shop will provide
You with ~38-Volts at roughly 3-Amps, ( check the Specification-Labels ),
and will also provide a Center-Tap if needed.
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.
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Pulsator coil that I want to drive is rated at 260 mA @ 24V or 540 mA @ 12V.

AC or DC?

 

AC or DC?

Thought I'd included it earlier but its DC.

(When one is using widgets designed and built for the mega corps it seems to become quite difficult to find good technical information. Its likely going to take me doing some serious testing to find more information (which would be quite useful!).)

 

Assumed DC but wanted to be sure. Nothing worse than making an assumption only to find out later that it was a wrong assumption.

 

Unless you want to build a linear PSU for the experience you can buy an off the shelf SMPS power supply for about $53 USD including free shipping with Amazon Prime. Once expensive power supplies using heavy transformers have been replaced with the SMPS types. Most include a nice digital display of voltage and current. Here is another example of a 30 volt 5 amp for $40 USD. I can't build one for that price let alone with digital display and current limit capabilities.

Ron

 

For the TS to have a power supply, adjustable for just a few volts and able to deliver up to 30 watts over that whole range, the whole project can be built from individual components for a reasonable cost, IN SOME PARTS OF THE WORLD.
THAT was the reason for the question as to location. In some areas both new and used parts and assemblies are quite cheap, even by local standards, in other parts of the world even a single small transistor is a few USD. So asking a location is a courtesy, not an insult. And the answer I read means not much. Never heard of the place by that name.
If the TS can live with a well filtered but not regulated adjustable DC supply, one can be built from surplus-store parts for about $100, that will deliver up to at least 30 volts at up to ten amps. It would use a VARIAC transformer to feed 24 to 28 volt transformer/bridge rectifier string, that had a few high value electrolytic capacitors as the filter. It could also serve to feed an adjustable linear regulator to provide a regulated output while avoiding excessive pass transistor dissipation. The price of the 300 watt variac could be avoided by using a switched tap arrangement single transformer.

But not nearly as convenient as my zero to 50 volt, zero to 50 amp, fully metered supply, that retails for $1200 to $600 (USD). I got that one for much less because it was listed "as-is, not working".
There exists also the option of buying surplus 5 volt switcher supplies and using them in series to provide the range in five volt steps.

 

Greetings

OK - - I've spent the $$$ and bought a supply of various different components (capacitors, resistors, ICs, etc etc) and have starting working on learning some programming but in the process of fabricating something (or anything for that matter) I would like to do something using first a breadboard but then to test circuits and software well I need a way to drive my stuff. Looking at products on alie, banggood, mr jeff's emporium, and the ebay jungle - - - - well what I'm struck by is that most of what I can find that is somewhat affordable (don't want to spend north of $1k!!!) for a adjustable DC power supply is stuff that seems to be quite throwaway. The better ones will work for a few hours of use over a few projects and then they're doa.

How do I find an adjustable (thinking 0-30V and 0-10Aat least) DC power supply that will last for a while - - - ie at least 10 or more projects and at least 100 hours of one time. Ideas - - - suggestions - - - tips - - - - please?

TIA

I'm not a pro but did study electronics in college for two years and it was my hobby for many years. One tip, always get better equipment than your likely to need. Not easy to define that but go up rather than down when trying to select equipment.

I have this:



and for my purposes it is very unlikely that it's spec is too poor for any projects. This was 400 bucks but I could have got one for 200 or even less, but I always aim higher than I need, I have decent test kit for my modest hobby needs and I can tackle many things and be confident the equipment will not be a limiting factor.

 

Actually, the last concept that I mentioned, would be a very good way to have a rather efficient supply that could provide a great deal of power for not that much expense. Five volt regulated supplies have been available as surplus for quite a while.
Consider one variable 5 volt supply and then a string of 5 volt supplies in series with it. And I have seen the 5 volt ten amp supplies for under $20, used, working, good quality. That could allow up to 30 volts at ten amps. The only drawback would be having to switch ranges every 5 volts.