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Is it still worth building an adjustable bench type 5-10 amp PSU these days?
Posted by nzo on 23 Aug, 2011 05:26 -
Just wondering about the economics of it (not counting DIY time and the pleasure
of building it)
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It is not very economic. Already the transformer and parts like metal case will cost half of a whole Made in China bench power supply.
This is typically the moment that someone chips in and tells us he build his bench power supply for 0.000314 Shekel only, and it can be done. Sure, if you happen to be lucky and happen to just have all the right parts in your parts drawer. And if they magically ended up in your parts drawer free of charge. And if you find it stylish to have an enclosure made from duct tape and chewing gum. You get the idea. -
LOL. I see your point.
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Speaking about cash, my Kenwood PD36-10A that is 36V 10A it has a true transformer and active cooling and the weight is 14 kilos.
And it cost about 1700$ USD
( just found the price today )
The PSU is the only device that you will keep for ever, this is why it worth's investing some true cash,
so to have something worthy for the years to come.
Unfortunately , with DIY there is no chance to archive truly worthy results, except if you make a direct copy the Kenwood PD36-10A.
http://www.texio.jp/english/product/power/detail/series_p.php?id=29
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That's a fine-looking PSU Kiriakos-GR. $1700 smackeroos...phew!
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That's a fine-looking PSU Kiriakos-GR. $1700 smackeroos...phew!
Do not loose faith, there is lots used.
In Japan they sell them for around 300$
Start exploring your own area and the Ebay. Australia
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LOL. I see your point.
I'd mostly agree with BAW, your DIY doesn't have to be a spit & duct-taped disaster. But you'd be hard press to produce anything that is robust and looks good for the equivalent of an off the shelf unit. Testament to that is the dearth of kitset power supplies, once they were common but looking through the catalogues there isn't much to be found. That's a pity because they were good starter projects, but commercial reality driven such kits well towards extinction.
At beginner level it may be worth the exercise to produce some simple 3 terminal regulator boards for specific tasks but again hard to justify when you can get quite reasonable regulated switchplug packs for a few dollars.
Looks at http://geoffg.net/Utility_Power_Supply.html for some inspiration if you'd rather DIY whatever the price. Consider mixing a combination of off the shelf SMPS with some linear regulators for a custom supply specific to your needs. But remember the cost of parts rises quickly to build anything decent.
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Why not go half way?
Buy a cheap Chinese bench supply -- which will give you the nice case, knobs, terminals, displays and possibly a half-decent transformer - then, if the rest of it is crap, build your own regulator and control circuitry.
You'll probably still save money over a top-of-the-line supply *and* have the fun of doing your own design/build of the exciting bits inside.
I have to admit that I've done this a few times before and often, when I'm buying Chinese-made engineering equipment for my workshop, I end up having to treat their lathes or mills as a "semi-assembled kitset of parts in need of finishing, upgrade and alignment". Still, by the time you've done the extra work, you can end up with some really good equipment for a fraction the "brand-name" price and with that little bit extra functionality or performance that you might decide to add along the way.
For example, I bought a Chinese lathe and decided the toolpost sucked so I made my own which is far better than the original. -
Dear nzo:
--I agree with virtually all of the previous posts (although UncleV will never know, because I am on his ignore list). My recommendation is before you build one of your own, I recommend you first buy a good used bench supply from somewhere other that Hong Kong. By buying used good stuff, you get quality at a Hong Kong price. And it will give you a good idea about design, case, layout etc., you might as well learn from the masters like HP, but some of the Heathkit PSU are very nice as well.
-- Have a look at this HP ALIGENT E3614A 48W 0-8V 0-6A BENCH DC POWER SUPPLY. These things are darn near bullet proof, you can get manuals, and they are repairable.
Buy it now $165, free shipping.
http://www.ebay.com/itm/HP-ALIGENT-E3614A-48W-0-8V-0-6A-BENCH-DC-POWER-SUPPLY-/330591680875?pt=LH_DefaultDomain_0&hash=item4cf8ccb96b
Best Regards
Clear Ether -
How about an old UPS? It already provides the most expensive components like case and transformer. Also the pcb is full of useful components.
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If you've never built a PSU, it would pay to build to learn, not for practical use.
Getting a used quality PSU from eBay can be challenging: is it worth $180, why is another $320, why is another $50, all the same model? Can you tell if there is a subtle fault that not even the seller knows? How do you test these PSU to know its up to snuff or repair it? From a box new PSU the manufacturer warrants the specs, but not if second hand from eBay.
In my day, there were no brick power supplies; so I built linear PSU for nearly all my devices; I think in the end I built 10, and I frankly got sick of it by 5th; I wondered why does each item need its own PSU when I don't use them all at the same time? Why not modularize it and plug it in only when I need it? Well, before I could work that out as a project I found them for sale and I haven't built one since [ somewhere ~ 1976-1982]. Likewise do the same for a SMPS, a doubler, a tripler, make it, test it, then dissemble it and reuse the parts for another project.
Many PSU of all sizes often end up in the garbage, and work. I find, collect and cannibalize them, and rarely have to buy any for projects ... but that's because you know how to build them, and take what you need.
You needn't create a full project, with a nice case, and all the trimmings. That's worth doing maybe 1-3x, in the end, since you can buy a lot of items or find them free in the trash, modding them for your needs is more practical, you can even find nice enclosures ... just check a dumpster near you, this is particularly wonderful at the end of the year in any major school; studs dump and research labs dump a lot of working gear. Enclosures from appliances can provide the sheet metal for you to work into real project cases. At the very most, you can get meters of high quality cable and copper wires.
Its also a green thing to do
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Power supplies are great projects to build, but economic these days? Not for the general purpose ones.
I'm working on a few lab power supply projects at the moment, but they are all unique in some way that you can't really buy off the shelf.
Dave. -
Keep your eyes open on ebay for faulty units. These can be a good source of parts if nothing else. Do a bit of research before buying (manuals, circuit diagrams etc ) If you can fix it you have a nice cheap supply if not you have a decent case etc for your own build. Repair, Reuse, Recycle
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Dear nzo:
--Saturation is correct, I should not have recommend that you buy second hand, without the standard caveats. If you are new to eBay, you will want to observe items in your area of interest, and get an idea of how things go before charging in.
--Subtle faults that not even the maker is aware of can occur with eBay, Hong Kong and DIY. Freethinker has a great idea about buying "non-working" and fixing or "parting out", but it takes a lot of research. But if the item is cheap enough you should be alright. In any case this is half way to building your own power supply. Since I am familiar with them, I buy old Heathkits and fix them up.
--Still, caveats being noted, there is a reason Dave and countless others recommend buying make and model numbers of known reliability and repairability. It' because you can get darn good stuff at a darn good price.
Best Regards
Clear Ether -
How about an old UPS? It already provides the most expensive components.............
The most worthy to pay characteristic is the low noise Ampere limiter.
Just because of this, it worth paying and getting a respectable low noise design.
The voltage control was always the easy part.
For example when I watch those 11 ADJ pots on my Kenwood I feel dizzy
How in earth I am going to calibrate this monster ?
And this is just the first PCB of the four in it.
( The picture is not my "Japanese Bloger" )
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Thanks all for the great replys!!
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I got a nice deal on one of these from eBay a while back.
http://www.wattpowertest.co.uk/2-0-30v-5v-triple-linear-power-supply-digimess-hy3003-3.html
The two main channels (<30V <3A) can run separately, series or parallel.
Nice n flexible.
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That's a nice looking PSU Kosmyk, and not too bad a price. I wonder if the sellers of these models follow the trend of having some or all of it made in China and then re-labelling it. Hard to tell these days.
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Yup. Country of Origin China.
Digimess used to be Grundig.
I guess most if not all mass produced electronics are made in one part of Asia or another.
I got my HY3003-3 s/h for £82 delivered.
I was pretty happy with that deal.
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Digimess used to be Grundig.
A long time ago. When Grundig went bankrupt the Digimess brand was sold separately. The new owner of the brand sells a bunch of badge-engineered stuff under the brand. The web site http://www.digimess.co.uk/ is good for a name-the-ODM bingo card.
Your Digimess looks like a Mastech power supply. People are usually satisfied with these. -
Well spotted. Even uses the same Model number.
Much cheaper with the Mastech badge on though.
I think it's allright.
Having to switch the metering between V & A can be tedious though.
And you have to be careful not to mess with the mode switches while switched on or connected to anything.
Certain unpleasant surprises can occur.
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Dear nzo:
--Have a look at this post from a different section in this forum. I might be helpful.
https://www.eevblog.com/forum/index.php?topic=4579.0;topicseen
Best Regards
Clear Ether -
LOL! Thanks for that tip mate It's on my things to do list.
BTW, you are the only person on any forum that has ever addressed me with "Dear nzo"
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LOL! Thanks for that tip mate
It's on my things to do list.
BTW, you are the only person on any forum that has ever addressed me with "Dear nzo"
I am aware of the story about the frog and the princes , and so do not expect a hag from me. LOL
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Kiriakos-GR - My friends who have been to Greece tell me they are warm, welcoming, human, hugging people. Even though ordinary Greek people are now much more stressed because of the huge financial burden that began with the Olympic Games and the meddling of bean counters and politicians who themselves don't know what the hell they're doing. None of them!