Looking for to build a Regulated ps 0-50 V and 0-40 Amps

[Fuster]

Hi everybody,

I've been looking for a regulated power suppy but the prices I found were quite big expensive to me in this moment so I want to see if its possible to build it by myself... but I need your help. What I would like to build is a regulated ps 0-50 V and 0-40 Amps. (40A is the continuous rating not peak). Does anyone have an schematic for something like that? Any help or commets are wellcome. Thank you very much for your help.

Fuster

[Wizpic]

That is one hell of a power supply to get 0-50V 0-40amp continous, I would say that would be one hell of a heat sink

Now you can see why there so exspensive, I do not have anything to help you but good luck

wizpic

[Parmin]

Ok.  First, you have to acquire a strong power source (AC -> DC) of the required rating.  I suggest a 2KW arc welder.
Why?  well, you require 50 volt at 40Amps ie, its a 2000Watts power supply.. its enough to cook you to crispy charcoal 

Then, you have to decide whether you will use linear power regulation or switch mode.  Linear regulation as Wizpic suggest in the above, will require HUGE heatsink and will create lots of heat.  On the other hand, to use switch mode, you will require either a massive bank of transistor or a HUGE IGBT or FET to do you power chopping. 
It is do able I think, but it is definitely not cheap or small.

The truth is I dont even know why on earth one would need one of those !!!

[Fuster]

Hi all. Thank you both for your quick response. Well, I promess you I don't want to buid an electric chair.  I suposed it wasn't be easy but after your coments I think am going to give up the idea... at least for 40 Amps. I think I am going to look for again for a comercial one linear and with less amps... around 15-20. My intention is start to experiment with electrolysis. Still any idea is good welllcome. Thanks a lot.

Fuster

[Alienbeing]

I purchased a Lambda power supply on Ebay that goes from 0-48 volts @ up to 70 amps with digital readout of volts and current for $70.00 US dollars and is one nice supply. Mainly use it to power up moble radio transmitters and amplifiers. Probably the point I'm making is it would be more then likely cheaper to look for a used one like on Ebay rather then design one the kind you need. Just the transformer alone on mine would have cost more then what I paid for the complete supply I bought not to mention the huge bank of capacitors it has and the copper buss bars.

Alienbeing

[Walkura]

You can build a regulated powersupply on the basis of a lm 723 with a lot of heatsink & transistors .
http://agurk.dk/bjarke/Projects/PowerSupplyFET/13.8V%2040A%20Power%20Supply%20Schematic%20Prints.pdf
A schematic like this is easy adjustable to your needs .
However to limit dissapation in your transistors you could consider to add a sort of ac-ac chopper .
The idea is basicly to place mosfets between the diode bridge and the main buffer elko
(seperate the mosfets from the elko with a big sckotcky diode)
With pwm signals to the mosfets you can create a pre-regulation that can save a lot of heat

Other option is ofcourse switch mode supply's .
The following link is to a polish elektroniks magazine .
Its a schematic for a welding inverter capable of delivering 1,5 to 2 Kilowatt
http://www.ep.com.pl/pobierz.php?id=12162
For as far as i know there is no english translation of it (sorry for that)
It is possible to adjust it to your needs .
But you will have to calculate the transformer for it .
A etd59 should easily do .
But thats no project for beginners .

Good luck .

[Fuster]

Very interesting you PS Alienbeing. $70 is a bargain... I know the price of the componets are going to considerably higher then that. I didn't consider until now a used one but it's also a good option for me right now. Could you tell me the exact model you buy please? I'm going to search google to see what I could find but would be interesting to know exact model.

In spite of that I'm going to take a look to Walkura's schematics... but now that I now that there is a possibility to buy a PS as cheaper as that one of Alienbeing...  Don't worry Walkura I will try with a translator and a dictionary... there is no knowledge without effort. 

Thanks both for your help

Fuster