Finding a DC power supply

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
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
 

LowQCab

Joined Nov 6, 2012
4,052
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.
.
.
.
 

AnalogKid

Joined Aug 1, 2013
11,021
How do I find an adjustable (thinking 0-30V and 0-10Aat least) DC power supply
What are you prototyping that requires 300 W? At that power level, what you are powering becomes a relevant factor in how you are powering it.

Where are you located?

ak
 

MrChips

Joined Oct 2, 2009
30,779
I am not a big fan of SMPS. If you want to begin learning while building your own electronics your first build would be a 5VDC 1A power supply using a traditional linear 3-terminal voltage regulator.

Next would be a 0-12VDC supply.
I have been using something similar to this for many years now for general test, repair, prototyping, battery charging.

PMC power supply.jpg
 

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
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.
.
.
.
Interesting - - - thanks for the info!

I was hoping to purchase something except I'm not finding much that's also reliable in the sub $200 can range.

Re: DIY - - - likely not a bad idea but I'm already working some 3 and sometimes up to 5 levels deep (you know project to build the project to build the project . . . ) kind of thing and was hoping I could trade some $$$ for a lot of time.
My guess is that a power supply like this would be an easy 50 hour project and I'm far more itching to get building and testing the stuff I need so that I can build the project to do what I want so that I have the material for the actual project.
If there are no solutions even in close to my price range I hope you won't mind if I come back and ask for guidance (pretty please - - - LOL).

Thanks for the ideas and assistance!
 

dl324

Joined Mar 30, 2015
16,896
Welcome to AAC!
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?
Are you sure that you'll ever need 10A? My advice is to get multiple power supplies instead of one "big" one. Before I bought a 30V/3A supply, I used a homemade (linear) supply that was my first project:
firstPowerSupply.jpg
One output is adjustable around 5V at 1A. The other is adjustable from about 4-18V at 0.5A. The posts are 5-way, but I added the reverse biased diodes on the outputs so I could connect mini-grabbers.

This Velleman is one of my last 4 power supply purchases:
vellemanOriginalTerminals.jpg
It's 30V/3A and cost around $75. I don't know (or care) if this one is a switcher.

My only complaints about this supply are that the jack spacing and jack order are goofy and the "safety" jacks are only one way. Spacing is about 0.85" instead of the more standard 0.75" and the order is goofy. Earth ground should be on the outside so a dual banana plug can be used. After being annoyed for years, I built an adapter. Couldn't use multi-way jacks because they were too long.
vellemanAdapter2.jpg

My last 3 purchases were Wanptek 30V/6A switching supplies. I waited until there were promotions at AliExpress and my cost was about $40 each. It's easy to spend more.

I bought the 3 digit display versions because they don't have an earth ground terminal. The posts are 3 way and the spacing is the typical 0.75".

You can see parts of 2 of them in the second picture.
 

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
What are you prototyping that requires 300 W? At that power level, what you are powering becomes a relevant factor in how you are powering it.

Where are you located?

ak
Project #1 is replicating whilst improving a externally controllable milking controller.
(Commercial units have limitations I need to break! The real meal deal items are hugely expensive as their in a captive market and I am quite tired of a billion $$$ outfit want to make a lot more money off me selling me not that good a c**p!)
So - - - the pulsator end is driven at 24 V (could be 12 V but for long term design reasons have gone to 24 V) and that takes some not much more than 500 mA (IIRC). Then there are the other functions (control etc) so its at the least a couple few micro-controllers or a small micro-processor. So that could be a bunch of sensors/drivers.

Located in the wilds of actual central Canuckistan (not by population but by measurement please) dunno what that has to do with the question though.

How does using over say 100 W make it necessary to how one is powering the apparatus?

TIA
 

dl324

Joined Mar 30, 2015
16,896
I'm far more itching to get building and testing the stuff I need so that I can build the project to do what I want so that I have the material for the actual project.
If there are no solutions even in close to my price range I hope you won't mind if I come back and ask for guidance
You can buy a couple used laptop supplies for less than $20 each. They'll be around 18V/4A. The outputs will be floating, so you can stack them to generate dual supplies for opamp circuits. Breadboard some LM317 to put on their outputs for adjustable supplies.

They'll be switchers, but who cares? Ripple isn't that bad and you should be able to filter it. If you put a linear regulator on their outputs to have variable outputs, they'll filter any ripple.
 
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Thread Starter

ajoeiam

Joined Mar 26, 2022
12
A well-built power supply will last many years.
Where did you get the idea it wouldn't?

It's unlikely you will need more than 1 or 2 A of current for your electronic projects.

Cruising through mr jeff's emporium and reading the reviews.
Some generally 10 to 15% actually talk about this.
Likely more should be be if you only use something once in 10 years - - - then longevity isn't likely an issue.
Me - - - I a cheap tight old sob - - - I don't like spending money on 'drek'.
Trust me - - my list of projects gets to needing more than 2 A at likely 5V (or maybe 3.3) long before #5.

Would you care to point me toward a 'well-built' power supply?

TIA
 

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
Welcome to AAC!
Are you sure that you'll ever need 10A? My advice is to get multiple power supplies instead of one "big" one. Before I bought a 30V/3A supply, I used a homemade (linear) supply that was my first project:
View attachment 311185
One output is adjustable around 5V at 1A. The other is adjustable from about 4-18V at 0.5A. The posts are 5-way, but I added the reverse biased diodes on the outputs so I could connect mini-grabbers.

This Velleman is one of my last 4 power supply purchases:
View attachment 311179
It's 30V/3A and cost around $75. I don't know (or care) if this one is a switcher.

My only complaints about this supply are that the jack spacing and jack order are goofy and the "safety" jacks are only one way. Spacing is about 0.85" instead of the more standard 0.75" and the order is goofy. Earth ground should be on the outside so a dual banana plug can be used. After being annoyed for years, I built an adapter. Couldn't use multi-way jacks because they were too long.
View attachment 311180

My last 3 purchases were Wanptek 30V/6A switching supplies. I waited until there were promotions at AliExpress and my cost was about $40 each. It's easy to spend more.

I bought the 3 digit display versions because they don't have an earth ground terminal. The posts are 3 way and the spacing is the typical 0.75".

You can see parts of 2 of them in the second picture.
 

WBahn

Joined Mar 31, 2012
30,008
You need to identify what you actually NEED now, as opposed to what you WANT or might need down the road.

When I first started playing with electronics, my power supply was almost always a 9 V battery and a 7805 regulator on the breadboard. If I was working with opamp circuits and needed a bipolar supply, it was two 9 V batteries center-tapped. Those were sufficient for doing lots of things.

Building a supply that barely meets your present needs is probably not very difficult -- just don't add features that you don't need. Even if you outgrow it's capabilities in short order, there will always be plenty of things that you will do that it will be adequate for.

There's no reason that a commercial power supply shouldn't outlast you. I don't think I've ever had a power supply go bad -- at least not that I can recall. If you are buying different brands and they are all failing in short order, it is almost certainly something that you are doing wrong to cause them to fail.

I've always had good results with B&K Precision supplies and there's a lot of used supplies floating around.
 

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
Wrote a reply to ls324 - - - I took too long - - - 10 min max time and over - - - you can't use your response.
I guess the idea is to keep everything a sound bite. Not exactly an appealing characteristic for a 'help' site.
 

dl324

Joined Mar 30, 2015
16,896
Wrote a reply to ls324 - - - I took too long - - - 10 min max time and over - - - you can't use your response.
I guess the idea is to keep everything a sound bite. Not exactly an appealing characteristic for a 'help' site.
I took over 10 minutes to compose my response to your post. Maybe it's a feature that applies to new members...

You should also be able to edit or delete your posts.
 

Thread Starter

ajoeiam

Joined Mar 26, 2022
12
I took over 10 minutes to compose my response to your post. Maybe it's a feature that applies to new members...

You should also be able to edit or delete your posts.
Then it would seem that they really don't want 'new members'.
Perhaps should and can is rather different in this instance. (Sorry)
 

dl324

Joined Mar 30, 2015
16,896
Then it would seem that they really don't want 'new members'.
Perhaps should and can is rather different in this instance. (Sorry)
I don't remember what limitations there are on new members. I know you can't create private messages until you have 10 posts. IIRC, there's also a restriction for posting in Marketplace.

Any restrictions aren't very onerous and you're close to 10 posts.
 

AnalogKid

Joined Aug 1, 2013
11,021
Then it would seem that they really don't want 'new members'.
Complete and utter borscht. Of all of the forums to complain about how they treat members, and there are *many*, this ain't any of them. I think there is a threshold of 10 posts before some rights kick in; the mods can let you know.

Located in the wilds of actual central Canuckistan (not by population but by measurement please) dunno what that has to do with the question
It tells us what kinds of components and devices you have access to, the quality of your electrical infrastructure, etc.

How does using over say 100 W make it necessary to how one is powering the apparatus?
Because there is huge difference between a power supply for a 200 W audio amplifier and one for an industrial/mechanical device, and as you can see in post #1 there is zero information about this.

ak
 

dl324

Joined Mar 30, 2015
16,896
@ajoeiam
I wouldn't have any problems with taking a chance on this:
1703874196719.png
This seller offers free delivery to my location. May not be the case for your...

I haven't had my Wanptek supplies long, but I did verify that they could provide the rated voltage and current.
 

ThePanMan

Joined Mar 13, 2020
792
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.
 

WBahn

Joined Mar 31, 2012
30,008
Wrote a reply to ls324 - - - I took too long - - - 10 min max time and over - - - you can't use your response.
I guess the idea is to keep everything a sound bite. Not exactly an appealing characteristic for a 'help' site.
Not sure what happened to you -- I have LOTS of replies that took more than ten minutes to write -- sometimes days before I submit.

There's really no way for the AAC server to know how long it took your to type your reply since the first it knows about it is when you post it -- everything else is in your browser.

While there are just a couple of restrictions on new members, they are purely aimed at inconveniencing people that join for the sole purpose of spamming the forums or hiding their tracks when they try to get members to help them cheat on assignments.
 
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