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

[sam_sam_sam]

Please watch the part of the video where she shows how the modification is done would this work

Move to the 3 minute mark where it starts

https://www.youtube.com/watch?v=HdNWrFOFFWI

[stj]

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

there are a lot of such projects,
the limit will vary with supply design and obviously all the output caps need to be uprated.
Danny-K (diode-gone-wild) has a website with usefull info
http://www.danyk.cz/

[sam_sam_sam]

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

there are a lot of such projects,
the limit will vary with supply design and obviously all the output caps need to be uprated.
Danny-K (diode-gone-wild) has a website with usefull info
http://www.danyk.cz/

What I am asking is will the modification to the switching power supply board and hooking it to buck converter

I know I have to add on diodes and capacitors for 35 volt rated capacitor on the auxiliary power supply board where she taps off the switching transformer output pins would this work or maybe 50 volt rated capacitors ones

How would you figure out what your maximum amperage output would be just from the auxiliary power circuit not to the buck converter

Do you use the rating for the -12 volt rail and this would your maximum amperage or there another way to figure out what the maximum amperage is for the transformer tapped output

[stj]

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

video didnt play for me,
i'm just saying, there are lots of atx mods.
most dont need an extra convertor.

if in the video he uses a 12v supply to drive a convertor then it will work but obviously you need buck-boost to be able to go both under and over 12v

how much does the buck-boost and displays cost?

[sam_sam_sam]

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

how much does the buck-boost and displays cost?

About $15.00 us

[stj]

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

that's pretty cheap.
if you can stretch to just over double that then the ruideng unit is better.
https://www.aliexpress.com/item/32840324731.html

[sam_sam_sam]

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

that's pretty cheap.
if you can stretch to just over double that then the ruideng unit is better.
https://www.aliexpress.com/item/32840324731.html

Thanks for the website link

When I do the switching power supply board modification I will post some pictures of it so you can get an idea of how she does this modification on the switching power supply board it only works correctly for isolated tap winding for 3 / 5 / 12 volt output and you tap from 12 volt to 3 volt which would the outside two taps on the winding you do have to use a volt meter or scope to figure out where you take the power from

I have one power supply that I tried this on but it would not work because it only has 5 volt and 12 output only from the main switching transformer

I took out the transformer and saw that most of the mounting pins are tied together and they are tied together on the board as well on the secondary winding

I have another style that has independent winding taps that are not tied together on the board so I going to try on this power supply board later on today and see if get around 22 volts AC if I do then I can go head and make the auxiliary power supply board and try this out and see what the results are but because these switching power supply were bought new / old stock surplus and have crap-e capacitors on it and they pop there tops already I will have to replace all the capacitors first before I can do any testing

One note these switching power supply as far as I know have never been used because they are very very clean inside

[stj]

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

so you use the transformer for 15v?
not sure what that will do to the feedback sensing!

if you have a buck/boost then why not just use the 12v??

[sam_sam_sam]

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

so you use the transformer for 15v?
not sure what that will do to the feedback sensing!

if you have a buck/boost then why not just use the 12v??

Because I also want to use the 24 volts for charging a battery pack that I am going to making and do not want to use a boost converter to do it

I just want to use a buck converter for voltages less than 24 volts down to 3 volts and anything in between but for 5 volts or for 12 volts because I already have those output unless I want to control current then I would use the buck converter for this purpose

In this particular modification she shows that you should be able to short the two wires together and it shuts down the power supply which I will be also testing this first with incandescent light bulb in series with the line in before it goes to the switching power supply board just in case s**t goes wrong

[eccerr0r]

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...

[sam_sam_sam]

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...

You are correct I have the same exact feeling that this might not work correctly but I going to give it a try because I have watched this video several times and have questions about weather or not it would work or not

And I am complied to answer this question one way or the other

[eccerr0r]

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

And I've seen a lot of PSUs connect the two diodes in a TO-220 dual diode in parallel, which completely makes the "mod" infeasible...

[noppa]

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

i would like to find the time to try this mod...

http://www.chirio.com/switching_power_supply_atx.htm

[eccerr0r]

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

Yeah that's much more interesting, and more efficient as you no longer have double conversion, alas as in the video in the initial post -

- Highly depends on the PSU to make a workable change to allow this
- There may be more circuitry changes needed...a lot more. The PSU may go unstable...

[sam_sam_sam]

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

Yeah that's much more interesting, and more efficient as you no longer have double conversion, alas as in the video in the initial post -

- Highly depends on the PSU to make a workable change to allow this
- There may be more circuitry changes needed...a lot more. The PSU may go unstable...

Where do I get ATX switching power supply with the type of board that they show because I do not have one that is set up that way

I have one that has the lm385 ic chip and another one small ic chip one but I do not have the part number information right now

Would someone sell me one or tell me which model numbers would have the same exact board that they have in the website site post

Thanks

[eccerr0r]

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.

[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.

What models would have the ic chip that you might be able to modify circuit

[sam_sam_sam]

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...

Actually I can get about 60 dc volts with a 100 watt light bulb hook up to a Schottky diode rectifier setup with no capacitors on the output yet but it does pull the power rails down a little bit ( this is with a incandescent light hook to the output ) but it does seem to work I do not have a setup yet to test the short circuit test yet but this will come next

I am a real dum a** yesterday when I was putting back in the choke you can put it in two different ways and of course I would put in the way it should not go in but had remove it because I need to hook some wires back up to the board and there in much remove were these go in

And of course I blew the fuse on the board then I hooked up the incandescent light bulb instead of the fuse for now the bigger light bulb is a 300 watt bulb I use several times for troubleshooting

[sam_sam_sam]

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

As you can see in the picture with the incandescent light bulb as the load I am getting around 20 volts but this is with out capacitors on the output I have not gotten that far yet tomorrow is another day to work on it some more

Does it look like it do able I think it might be but more testing is needed before I come to a conclusion about this modification to this type of switching power supply

There is a correction about what I have above it was supposed to be have been that with the load the voltage is about 21.00 volts and with no load it about 60 volts I could not edit it anymore


Unfortunately I do not have very many 100 volt capacitors and ones that I have are very low UF values
So it might be awhile before I can get back to this project because right I do not the funds right now to do anymore to it


More to come

[sam_sam_sam]

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

Ok update

I hooked a couple of 150 UF capacitors that I have on hand and to see if this makes a difference and it does the output the capacitors were in parallel configuration

With out a load the voltage is 60 volts with a load of 100 watt incandescent light bulb the voltage is about 52 volts

So now I have to figure out what the UF value need to be for best performance and go from there

Now there is a slight issue with the tester that I am using to run the switching power supply it is showing a over voltage on the 3 volt rail and the 5 volt rail sometimes and under voltage for the - 12 volt rail if you are running the auxiliary power supply board however if you load the 12 volt with about 2 amps or so everything goes back to normal

Which is very interesting results I was not excepting these results

Now these might change when I get the right UF value for best results because with out capacitors the over voltage on the 3 and 5 would be going on all the time with no load on the 12 volt rail

Also the 300 watt incandescent light bulb is just glowing a little bit and my current sensor meter ( has been modified to run on 5 volts rail ) is showing one or more amps with the 12 volt rail is load with about 2 amps and a 100 watt incandescent light bulb on the auxiliary power supply board

( now on my bench power supply with the voltage maximum 50 volts it is showing about 500 milliamperes so the total load might 3 amp on the secondary side of the power supply )

This project is now on hold until I have more money to buy some more circuit board material and some more 100 volt capacitors and more Schottky diodes and make a proper board and put it in switching power supply case to do more testing

This setup I have been using to do this testing makes me uneasy to do anymore testing with this make shift setup because I do not have what I need to do rest of the testing safely

The main reason for building this device was to use a buck converter to vary the voltage output but now I have to find one that can handle 80 volts on the input

But another use I have for it will be powering LED modules that require more than 50 volts because that is the maximum voltage my bench power supply is an I really do not want to use a Variac transformer setup because I have not found a isolation transformer to use it safely for one of its purposes

Because the isolation transformer are out of my budget for what I am willing to spend on one

Now I found one on eBay for $100.00 that would handle 3 or 5 amps I can not remember correctly which one it right now and might consider this one but I would have to have this amount of money on hand and have nothing else or project that are not a high priority to do at the time

Now if anyone has a suggestion for buying one or making one with out it becoming a major project I am all ears