Please comment on this modifying a ATX switching power supply is this a good idea

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

Well, tough to find exact PSU models that match but probably best to avoid Deer with COTY controllers.

That being said I think Antec Smartpower SP350/400 has that topology. But no guarantees.

If you have any suggestions about buying one that ( you know for sure has the right setup ) has the ic chip that would be similar to what in the article please let me know because I would like to test this idea myself and see how well it would it work and weather or not it would correctly with out any issues ( with out costing an arm and a leg to buy one

Because I have looked at all of computer switching power supply that I have and none have this setup

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

If anyone has any test that they are interested in on this project that I can feel comfortable doing it safely and have the right parts for with the setup that I have right now please post it before I take this setup apart and put it on the shelf for a while and I will be taking the auxiliary board apart and putting the Schottky diode back in the computer switching power supply that came out of

Because I have another project idea that I want to get answer about and see if this concept would work or not

I have to the conclusion that this concept will work if you plan how you are going to use this setup and use it with some restrictions on the use of the auxiliary power supply board and some what load the the 12 rail to keep the other voltage rail running in specifications that it suppose to work at it can be done correctly however I do not recommend this to anyone else unless they have a complete understanding of what the limitations are on this setup

Does it have a purpose as far as I am concerned it does but I would be very cautious about how I would use it and for what I would use it for

I have seen a lot of modification on the internet and I know for sure that some of them full of crap because I question how it was put together and what testing was done but this time around I found that it might be possible ( or in some cases it was to complicated to even think about doing it safely and correctly )

Now granted she was using the 22 volts for her setup which I could have used and might do some testing on this as well and if testing reveals that it also works and is more stable then what I might do is have a switch setup that I can switch from one to another winding tap ( this has to be tested in more detail before I can determine weather or not this would work or not )

If anyone has any comments about this project please feel free to to post them I am very interested in what all of you think about this project

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

Update
I made a proper circuit board for this auxiliary power supply board and did some testing today with it

I used ( 4 ) 150uf@100 volts ( 1 ) 100uf@250 volts capacitors for a total 700uf

at 500 milliamperes the voltage is 52 volts ( 100 watt incandescent light bulb )
at 1400 milliamperes the voltage is 39 volts ( 300 watt incandescent light bulb ) —> I only have two of these

Unfortunately I do not have any more incandescent light bulb more than 100 watts
and do not have any more light sockets for light bulbs right now so no quiet sure how I am going to do anymore load testing to do this with a light bulb instead of the fuse

I do not want to load test the hell out of it with out having more light bulb instead of the fuse just in case s**t goes wrong

The testing was done with the switching power supply board out of the case with no fan cooling the heat sinks so I did not run it for long periods of time

Tomorrow I will put it back in the case and do some more testing of it and maybe torcher test the auxiliary board and see what happens but I know that I can at least load it 1400 milliamperes with no problems

[brethin]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

I'd be surprised if typical ATX PSUs can supply 24V like that due to design compromises to reduce cost, but depends on the actual supply...

It can't without almost a full rebuild.

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

Update

Ok did some more testing and found out that the current limit is about 1.5 amps @ 40 volts

If you try to load it more than this voltage drops this might be because of the -12 volt rail is limited to I think to 2 amps

I did a short circuit test on the auxiliary board I shorted the power wires together and then turn the power supply ON and it tripped the protection circuit when I remove the short and turn back on the power the switching power supply came back to life

So the protection circuit still function correctly

Now I going to do some testing with it hooked to the 22 volt setup and see how it function this way and see if I can get more amperage out of it I might be making another auxiliary board because I did not use heavy wires between the diode devices that I used and they have a rating of 10 amps anyway but I can use the board that I have to see if I can get more amperage out of the output rail from the auxiliary board

Here is some pictures of the new auxiliary power supply board


Well I did some more testing and found out for some reason you are limited to about 2 amps ( because the more you loaded it the more the voltage output goes down and the amperage does not go higher than about 2 amps) when you do this type of modification which for what I going to use it for will work prefect for because there are times that I need higher voltage but current limiting ( for testing LEDs modules )

This winding setup is at 40 volts no load and load it about 30.something volts

But the more you try to load the auxiliary board it changes the 5 and 3 volt rails either the 5 volt rail goes little high and 3 volt rail goes a little bit low or it is the opposite way 3 goes high an the 5 volts go low according to the ATX testing meter module which is very interesting to me about these results

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

Update
I have put a selector switch to go from 30 volts to 50 volts winding and now it just a little matter of putting the fuse back in and reinstalling the switching power supply board back in it case and put the auxiliary power supply board in a ATX case by it self with a small fan and the meter module and the binding post and all the rest of the hardware

Put labels on the output binding post that the maximum output amperage is 1.5 amps of working amps

At about 2 amps it trips the protection circuit

Ones I have everything put back together I will try loading the 12 volts and 5 rails a little bit more and see if I can load the auxiliary power board more or not

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

Update

Yes you can do this modification to a ATX switching

( depending on the switching transformer setup this will not work on everyone of them )

power supply as described in the website link that I posted earlier using the incandescent light bulb instead of the fuse was limiting the output auxiliary power supply board and not giving the full amperage

The over current protection circuit still works correctly I shorted the auxiliary power supply output leads together and it turned off and when I remove line power supply it restarted again

As you can see the amperage meter shows 4 amps current draw from the AC input on the ATX switching power supply

The voltage with no load is 75 volts on the auxiliary power supply board

3 amps @ 50 volts on the auxiliary power supply board and about 1.5 amp on the 5 volt and 12 volt rail

You do have to put a small circuit load on ATX switching power supply board for it to work correctly and stabilize protection circuit to work correctly

Now I am doing a burn in test on this modification to this ATX switching power supply to see if any issues develop I still using the electronic fuse testing box that I built a very long time ago

The original picture was over 4.75 megabytes so I split the picture in half so you see how I am testing this switching power supply board with the modification made to it

So far it has run for an hour already and still working

I just realize that two pictures that I posted earlier were the exact same picture of the auxiliary power supply board I just posted the other side of the board

******Disclaimer notice******

I would highly recommend that if want to experiment with doing this type of modification that you frist make sure that your ATX switching power supply work correctly first before you start

I would highly recommend that you remove the fuse from the switching power supply board and use a incandescent light bulb instead of the fuse

I would highly recommend that you build a bridge Schottky diode rectifier assembly with a heat sink and use 100 volt capacitors

And above all please be careful and use caution while measuring voltages and current on these boards

********

How I going to use this setup is to use the regulator ATX power supply rails and or use the auxiliary power supply board by itself or a combination of the two

[sam_sam_sam]

Re: Please comment on this modifying a ATX switching power supply is this a good idea

I definitely have to put a little fan on the auxiliary power supply board because after running almost 2 hours and I had to go somewhere I turned everything off and checked the heat sinks and that one was very very warm and needs a fan every thing else was good

The only air movement is the over head fan on low speed and the heat sink was on its side so of course this does not help with cooling of the heat sink