You need current limiting to protect the power supply from short circuit, beyond that, an adjustable current limit can be helpful but seldom needed.

 

I thought it would be more expensive, but in a big chinese on-line shop Aliex*** (I don´t know if here I can put that kind of links) I have seen one of 480W 48V 10A with variable voltage and current for 50$. I know there won´t be a great PS but for my experiments it´s Ok i think

 

Just keep in mind that a lot of stuff from those on-line places are junk. They may work fine for you for years, they may work okay for awhile, or they may kill you on the first go. Then again, the same can be said for some of the projects you will likely be building as you learn.

If you go that route, check out the supply a bit after you get it. Take some measurements (like open-circuit voltage output) with it and the meter sitting on a bench with nothing flammable nearby and turn the power on from a light switch, if possible. Assume it's a poorly made piece of crap that is going to do its best to electrocute you right out of the box until your tests, done with this thought in mind, convince you that it's not. You should be able to establish how well it is working (at least in term of it doing things like catching fire or applying line voltage to the outputs) in ten minutes to a half hour, so it's not a huge inconvenience and could save your life (though it is doubtful that it is that bad, but you don't want to find out the hard way).

 

Just keep in mind that a lot of stuff from those on-line places are junk. They may work fine for you for years, they may work okay for awhile, or they may kill you on the first go. Then again, the same can be said for some of the projects you will likely be building as you learn.
...

While the high quality stuff is not junk, they don't make them like they once did.

I've made vendors nearly crap their pants by requiring a robustness smoke test (repeated dead shorts at full power, dump load tests from large electromagnets) on any 'improvement' that involves modern power supplies. I've had nothing but issues with high quality stuff from Lamba, TDK, Sorensen, etc... They all look great on a bench but most can't make the very high EMI generated from plasma source generation and ion acceleration like the old SCR/transformer big iron models could. The fancy LCD screens go blank, QEI encoders inputs die, output filters go boom!

On paper these guys look great but we fried one per week until it was replaced one from TDK-Lamba that only fried once a month while the original supplies lasted decades.

https://www.powerandtest.com/power/dc-power-supplies/xg-1500
https://product.tdk.com/info/en/catalog/datasheets/genesys_e_1u-750w-1500w.pdf

We finally had to modify (and add extra hardware filters) our control software just to turn the power supplies off for manual recovery after a series of detected arc events before they smoked.

Example: https://forum.allaboutcircuits.com/threads/dealing-with-negative-resistance.107553/post-823676

 

When I was working at NIST we had supplies that delivered up to 150 A of current to magnets having over 100 H of inductance. You can bet we didn't buy those from just any source or hook them up without extensive testing in house.

When doing work that stresses a supply, additional testing is certainly warranted. I don't think the TS is going to be in that category any time soon, and not with the supply they are looking to buy at this point.

I would, in general and broad brush strokes, agree that a lot of today's equipment is no where near the level of ruggedness that things use to be, even from the same vendors (in some cases even the same product lines or even model numbers). Some of that is due to a widespread need to cut costs in order to stay in business against cheap, low quality crap that has grabbed an unfortunately large share of the market -- and we the consumers have to accept our share of the blame for that. Some of it is intrinsic vulnerabilities of modern integrated technologies compared to older technologies. Some of it is cultural, in one way or another, where companies don't value having an earned reputation for quality as much as they used to.

 

I can't even count the number of tools I've bought over the years that I've ended up never using even once

What's happened to me is that I've not only bought gadgets that I've never used, but I've also bought them twice after completely forgetting that I had already bought them before... the poor things laying around still in their unopened boxes.

What that tells me is that women's "shopping gene" is a myth... us men have the same gene too, just focused on different things.

 

As I'm going through everything in the house as we move to the new house, I'm coming across many things still in their sealed box. Many different causes: sometimes I bought it but by the time I needed it I couldn't find it and so bought another; bought it and ended up not needing it (wrong thing for the job at hand, found a better way, decided not to do it at all, etc.), bought it because I could see how useful it would be to have. A few others, but it's that last one that really chaps me. To try to cut down on the unnecessary buying of things I already have, I am getting rid of stuff pretty mercilessly -- if something is in a box that hasn't been opened for, in some cases, three decades, clearly I don't need it. I have to have a specific reason for keeping those things. I haven't been perfect, but pretty good -- I've gotten rid of about 80% of everything in the Greater Wall of Stuff (and over 90% of my collection of clothes). I plan on doing another culling on the stuff as I set up the lab at the new house. Basically, nothing is going to be in some box shoved in a closet somewhere. I have some shelves that will have transparent containers and bins for parts and limited shelf space for odds and ends. Everything I keep has to be easily locatable and accessible, otherwise there's really not much need to have it. Now we have to just see how successful I am at achieving this and, even more to the point, maintaining it over time. But at least I'm hitting a pretty hard reset right now.

 

The endless boxes of never used stuff problem is solved for me. My oldest daughter is buying their first home just across the river in WA state. It's time to load up the truck with house warming gifts.

 

Gosh dad! How did you know I was thinking about buying a grid dip meter?

 

Hey pa, an SWR meter under the Xmas tree would be nice!

 

The endless boxes of never used stuff problem is solved for me. My oldest daughter is buying their first home just across the river in WA state. It's time to load up the truck with house warming gifts.

My parents pulled that with me. After I bought my first home, every time they would visit they would bring a few boxes of my stuff that had been sitting out in their garage for years. I would usually just move the boxes down to the basement without even looking in them. One day they brought a bunch of stuff over and I actually looked in the top box and nothing in there was mine. When I pointed that out, they said, "It's yours now. Enjoy." A quarter century later and I'm finally getting around to sorting out those boxes.

 

Thank you for the advice! If I buy it, I will be careful, but now I have my doubts!

 

While the high quality stuff is not junk, they don't make them like they once did. [...] They all look great on a bench but most can't make the very high EMI generated from plasma source generation and ion acceleration like the old SCR/transformer big iron models could. The fancy LCD screens go blank, QEI encoders inputs die, output filters go boom!

Hear, hear. When it comes to durability, big iron is king. No switchmode or linear solution will ever take as much abuse as a line frequency transformer paired with a high quality rectifier.

For instance, I've got an old 24 volt, 50 amp variac-transformer-rectifier power supply that will handle 100 amp overloads indefinitely so long as the brush position is not adjusted during overload. It'll get lukewarm after maybe 15 minutes or so. Try that with an SMPS and tell me what happens.