OK, for what ever reason, I have never picked up a true bench power supply.

I have a hand full of odd "junk" but never a decent supply .. and never one with current limiting. I just keep looking at them and saying "I can get by with what I have" ... even if it meant hooking four 6 volt batteries together to get 24 vdc.

OK, so I finally decided I want a supply.

I am a true hobbyist. I will not only use my supply for electronics but for battery charging, plating .... just about everything.

I have a limited budget ... though I was hoping to spend about $50, lets say $100 max.

Because I use it for everything, I wanted a Linear supply not a switching supply (things like plating ... I was restoring an old radio and needed a very small part plated) require this.

Do they even make what I am looking for for under $100?

I found all kinds of "cheap" supplies 0-30V 10A on ebay and Amazon for about $50 ,,, but they are all switching : https://tinyurl.com/y5hkv5qp

I did find a linear supply ($80) but it was only 5A : https://tinyurl.com/yy3fn8xf

If someone made this one in a 10A version for say $20 more, I would buy it.

I was really hoping to find a 0-30 10A linear supply.

I even thought about building one but not sure where to begin (I don't even understand how they set the amperage since I thought you need a load and it just draws as much current as required) ... and transformers seem super expensive.

Any suggestions or recommendations?

Thanks .... Mike

 

hi xtal,
If you want 24Vdc at 10A just for plating work, this is one option.
https://www.amazon.co.uk/10AMP-Vehi...973&sr=8-6&keywords=24V+lorry+battery+charger

E

 

OK, so I finally decided I want a supply.

I am a true hobbyist. I will not only use my supply for electronics but for battery charging, plating .... just about everything.

I would consider dividing up those applications and not trying to use a single power supply for all of them. For electronics on the lab bench, I've never wanted more than a few amps (to run a peltier module) and most projects are less than an amp. An old computer PSU can be had for free (from the e-waste recycle dump) and makes a fine power supply for electronics hobby project work.

 

That is exactly what I an doing now (well close).

I had a very old (I am 56 and had it since I was a teen) battery charger ... just a dumb one, not even a trickle charge on it and ... and used it for the plating. The problem is it was only 6/12 volts ... really needed 24.

I did a quick check just now on amazon and ebay. All our "dumb" US chargers are 12 volts only (or 6 / 12 volts) ... and it seems "dumb" chargers seem to be hard to find. There are 12/24 but they are all switching (smart) supplies.

I am using a computer supply now .... but I don't get the 24 volts I am looking for and no current limiting.

And again, there is the budget (sigh) ...

And because I find myself doing a bit of everything, I don't want to invest a lot in a supply that will only serve on need.

Thanks .... Mike

 

If you want to save money forget about trying to fill all your needs with one supply. You will be looking into spending $500 or more.

I would suggest looking into getting three supplies to cover most of your needs.

1) One or a number of low cost wall adapters for low current, low voltage applications. Costs no more that $2 each.

2) A mid-range bench supply, 50-100W.

3) A 12V battery charger or one to fill your charging needs.

 

Hi xtal_01.. im curious, why are switch mode supplies no good for plating?

You made me have a look inside a couple of supplies I have here, one is one of these:
https://www.aliexpress.com/item/KA3...lgo_pvid=61fd995c-394a-422e-be44-7657279f02f2

Im not actually sure if they are switch mode (?):


At least they have an old school transformer in them, and a big ass heatsink cooling something in the back, and no obvious other transformers or inductors). Certainly very different from the switch mode power supplies for computers etc. (As isn't it actually quite hard to make a good switch mode supply with adjustable voltage, as everything is tuned and optimised).

 

I am not sure of the "why" but I know when ever I go on plating sites, they said not to use a switching supply.

What you have there is what I am looking for! At least I believe it is. If it was a switching supply, there would be no reason for a transformer..... or am I wrong (someone can check me on this)?

You must be in Europe (I wish ... medical care for all ... oops, save that for another forum) .... I see it is 220 v input. I will search a bit but I should be able to find one with 120 VAC / 60Hz input.

Have you had good luck with this one?

Thanks .... Mike

 

300 W output means at least a 400 W transformer. That's big. 0 to 30 V and 0 - 10 A both in single ranges (no hi-lo switches) means a lot of excess heat; that means fans. Overall, this thing will be relatively large and heavy. The expensive parts will be the transformer, fan, heatsink, and meters.

If you are good with all of that, start with the transformer. To reduce thermal stress and heatsink/fan size, consider a center-tapped transformer and a high-low voltage range switch. If you need the 10 A only at low voltages, consider two power transformers with the outputs in series. There are a lot of options here, depending on what you have and what you can get within budget.

ak

 

If it was a switching supply, there would be no reason for a transformer..... or am I wrong (someone can check me on this)?

No.

Relative to a linear supply transformer, a switcher's is smaller, lighter, and uses significantly different magnetic material. But for any supply with outputs that are galvanically isolated from the AC mains, there's got got got to be an XFMR.

ak

 

Hi xtal I was thinking along the same lines, not much like a switch mode, unless it had a fixed low voltage DC which it then switches to the desired voltage, but as I said, no obvious inductor.

I have not used it all that much, as its very heavy! I went for a USB interface - delux model, so I could monitor in's and out's for calculating some efficiency on a project It does have one annoyance I seem to remember, it has a digital "twiddler" on the front that you use to increase / decrease the current and voltage limits, digit by digit, and it seems to skip a little erratically sometimes nowadays... 1...2...3...6..2..0... kind of thing. (though my microwave does the same!)

If you are using quite a bit of power the fan kicks in and it IS enthusiastic!

 

No.

Relative to a linear supply transformer, a switcher's is smaller, lighter, and uses significantly different magnetic material. But for any supply with outputs that are galvanically isolated from the AC mains, there's got got got to be an XFMR.

ak

Then actually many other bench supplies may also be non switching. I have a cheaper lower power chinese supply:

and it also has the same sort of layout inside old transformer, plus BIG heatsink on the back.

 

Exactly WHY can't you use a Switch Mode Power supply for electronics, plating and battery charger - Everything ?

 

I have a cheaper lower power chinese supply:.

99% sure that is all linear inside. Part of the problem for a switcher is keeping it stable across a huge range of voltages and currents. It is possible to build an all-switching "lab" supply, but it is more difficult that simply filtering the hell out of the output. HP ( > Agilent > whatever), Sorenson, etc. used to have them, especially for the high power models.

A hybrid trick is an adjustable switching supply followed by a tracking linear regulator set a few volts lower. For example, when the output is adjusted to 24 V, the switcher produces 28 V; when the output is set to 3 V, the switcher produces 7 V. This dramatically reduces the heat generated.

ak

 

OK, for what ever reason, I have never picked up a true bench power supply.

I have a hand full of odd "junk" but never a decent supply .. and never one with current limiting. I just keep looking at them and saying "I can get by with what I have" ... even if it meant hooking four 6 volt batteries together to get 24 vdc.

OK, so I finally decided I want a supply.

I am a true hobbyist. I will not only use my supply for electronics but for battery charging, plating .... just about everything.

I have a limited budget ... though I was hoping to spend about $50, lets say $100 max.

Because I use it for everything, I wanted a Linear supply not a switching supply (things like plating ... I was restoring an old radio and needed a very small part plated) require this.

Do they even make what I am looking for for under $100?

I found all kinds of "cheap" supplies 0-30V 10A on ebay and Amazon for about $50 ,,, but they are all switching : https://tinyurl.com/y5hkv5qp

I did find a linear supply ($80) but it was only 5A : https://tinyurl.com/yy3fn8xf

If someone made this one in a 10A version for say $20 more, I would buy it.

I was really hoping to find a 0-30 10A linear supply.

I even thought about building one but not sure where to begin (I don't even understand how they set the amperage since I thought you need a load and it just draws as much current as required) ... and transformers seem super expensive.

Any suggestions or recommendations?

Thanks .... Mike

I have never owned a bench PSU, and the ones I used at college were OK for curriculum exercises formulated to work within their limitations - but not all that much else.

Left over wall warts are fairly available, and good enough for a large proportion of "typical" projects. For higher power, its usually not too difficult to get salvaged industrial or IT gear switchers. ATX PSU boxes are a good example - once you know the rules for getting them working right.

Even a cheapskate bodger like me hardly ever uses a regular PSU for battery charging - its fairly easy to ruin nickel chemistry cells, and getting it wrong with lithium cells can ruin your whole house.

There are designs floating around the web for plating power units - it just makes sense to build a specific one of those rather than wrecking a PSU you use for other things.

 

OK, for what ever reason, I have never picked up a true bench power supply.

I have a limited budget ... though I was hoping to spend about $50, lets say $100 max.

Because I use it for everything, I wanted a Linear supply not a switching supply (things like plating ... I was restoring an old radio and needed a very small part plated) require this.

Do they even make what I am looking for for under $100?

Any suggestions or recommendations?

Do consider a used supply. You can try eBay, or one of the many used equipment dealers. You will get more for your money that way.

I would also think you'd want to divide up your budget and get something decent for the bench that is only about 5A up to ~32V and buy something else for high current that's not as nice.

 

Awesome guys!

You have given me a lot to think about.

I don't mind used equipment ... for what I am doing, that would be great.

Interesting, I didn't think about two supplies (or a split supply) with high and low.

It seems a switching supply is the simple end of the question ... a linear supply (even say one with just one or two fixed voltages 12 and 24 volts) is the difficulty.

And I thought this was going to be something "simple" ....

Thanks so much !!!!!!!!

Mike

 

I suggest going to the website "schematics for free" and then going to the "power" section. They have lots of circuits that you can download.
One way to have a nice power source, not regulated but quite stable, is to locate a powerstat or variac, which are variable autotransformers. They come in a wide range of ratings. Then, for the different voltage and current ranges, get step down transformers from used equipment, which if you are lucky can be had for the scrap price, or cheaper, or even free. You will need to buy the bridge rectifiers and filter capacitors, I recommend new on the capacitors but rectifiers are either OK or failed, do not buy the failed ones. This gives you a means of getting adjustable voltages in a wide range, one range at a time. Not regulated but that is not always needed. And the same supplies can feed a regulator when needed. And you probably will not spend even $50 unless you go purchasing new everything.

 

You may want to entertain another option. Consider building your own power supplies to suit your needs. As you are already a collector of e-waste surplus electronics you may already have most of the components needed to build a fixed or variable voltage PSU for under $20. For a few additional dollars, you can add a digital panel meter for voltage and current readout.

 

You may want to entertain another option. Consider building your own power supplies to suit your needs. As you are already a collector of e-waste surplus electronics you may already have most of the components needed to build a fixed or variable voltage PSU for under $20. For a few additional dollars, you can add a digital panel meter for voltage and current readout.

That is basicly what I was suggesting, although often old filter capacitors are not as good as one would like. Thus the suggestion that they be purchased new. Finding a circuit is sometimes a challenge, hence I suggested a reliable source.

 

10A is the problem.
http://www.eevblog.com/forum/testgear/decent-bench-psu-quality-used-or-cheapnew-from-china/