Try searching online for the Molex crimp housing part number (link below) - you may find ir or an equivalent locally or thru eBay (far east?)

https://www.molex.com/molex/products/part-det … ings/0903311003

I have idea to solder standard ATX slot to the motherboard too. Of course there is necessary to change wires or do it through short cable. Then I can connect standard ATX power supply.

What about just buying a atx to at adapter?

https://www.newegg.com/p/1W7-007D-00014?item= … 0QaArNbEALw_wcB

I recommend buying a converter that also supplies the -5V that ATX does not supply. I believe it was used by certain ISA cards. Also, one with a dummy load on the 3.3V rail since AT doesn't use it. Leaving it floating could cause stability issues in the ATX power supply.

ATX to AT adapters, which one do I need and why?

Any source for the -5V version on Ebay? I see the chinese ATX/AT converter for $3 but can't find this.

i bought the -5v version on ebay like 3 years ago
I wish i bought more, but only got 1, i cant find those anymore

the difference is just a couple cables that are connected to a white plastic square and another round component, that in terms of electronics i have no idea of what its name is.

this is the one i bought
in case you want to modify one of the non -5v available even on china sites like aliexpress.

but i dont know what are these 2 components, maybe someone on vogons has a clear idea of what they are :

1) white rectangle; (searched the words on google and found nothing)
2)black circle covered with rubber (wich connects to the white wire that makes -5v), i dont want to take the rubber out to look whats inside because i could need to cut it.

The white rectangular part looks to be a dummy load of some kind

Curiously, up until now I have been using ATX power supplies (mostly mid-end to high-end versions) wired to AT connector without any load on 3.3V rail and no issues whatsoever.

But I am curious about the dummy load: on the photo I can see a 20 Ohm resistor rated for 10W, which at 3.3V would correspond to 165 mA of current and ~0.5W of power. The load seems to be very small and resistor seems to be rated for much higher wattage, so what is the deal? Would a 20 Ohm / 2W resistor be sufficient for that purpose?

The white thing is the dummy load. It is a ceramic resistor.

The other thing is a shrink tube wrapped circuit that provides the -5v for power supplies that don't supply -5v by themselves. It is actually a pretty simple circuit.

See here for more info:
https://forum.allaboutcircuits.com/threads/pc … mputers.128266/

It is a shame that the eBay seller antronst is no longer selling them as there is a definite market for them. Maybe they weren't making enough money or were not able to source some of the needed parts anymore.

I have an actual pile of ATX supplies with -5, it's really not that uncommon

Sorry for the bump, but I do need that too (well, for many retro computers of mine actually), including -5V support.. Is there anyone that could suggest me a link to buy it?
Any clue?

Get any ATX to AT adapter. Then get a 7905C (cv, cp, etc BUT not a 79L05) or UA7905C. also need two small caps, a ~2.2uF and a 1uF. Input goes to the -12v line, output to the AT connector pin.
Mouser carries, L7905CV for $0.79, or L7905CP for $1.41 or UA7905CKCS for $0.96. Total with caps about $3 max plus shipping. You do not need a heatsink on it from my experience. Use some rubber tape to cover.
Make sure your ATX can deliver 0.5A or better on the -12v, some cheap ones only have max of 0.3A....
datasheet link: https://www.mouser.com/datasheet/2/389/l79-1849327.pdf
source: https://www.mouser.com/c/power/power-manageme … larity=Negative

Inverting regulators are also very common and work nicely, although you need to take a bit more care in filtering.

Good thought, that way could use the +12v ! I was looking at a few premade ones a while ago, this was in my history: https://www.ebay.com/itm/174976929699 best to add the mentioned 470uF cap to help with ripple....

I bought one as well from the guy on eBay he said he used a good quality -5 volt converter instead of the low quality ones from elsewhere, I bought two from him a 20 pin and a 24 pin and they work great, I'm interested in making my own just like his with a -5 volt converter and a 5 or 10 watt resistor to sell to people once I have made them, I have all the soldering gear and crimping tools I would just have to source where to get the same converter or one in the same size and quality, I removed the heat shrink on one of my converters to find more info on it but I didn't find any on google can someone please have a look at the pictures below, my google searching is not that great. Also it draws from the +12 volt and not the -12 volt

Interesting. Can you show a full picture of the adapter cabling ? The datasheet for ACT4070YH is same as the ACT4070B series and is not a Negative output (of course the data can be wrong). And every source is China.
Best you look for an equal part that can be found on Mouser or Digikey.... just my observation

Horun wrote on 2023-04-16, 03:41:

Interesting. Can you show a full picture of the adapter cabling ? The datasheet for ACT4070YH is same as the ACT4070B series and is not a Negative output (of course the data can be wrong). And every source is China.
Best you look for an equal part that can be found on Mouser or Digikey.... just my observation

Sure will but in about an hour I'm using it to scan memory on a 286 atm with 3 passes

Here's the 20 pin adapter pictures I put a piece of paper between the cables to see them clearly