Sphere478 wrote on 2022-10-31, 21:42:

You guys crack me up. Happy frankensteining!! Yes do keep us updated!!

Today I've managed to install one of your PCBs in my 'Frankestein' board and... it works!! 😀

I didn't have time until today to test it and also found that the TNT2 I wanted to test with was broken so had to order one of those chinese RageXL that I also wanted to try since I've watched Phil's video, so quite a good oportunity to spend 10€ for the sake of science hahaha.

Before soldering in I tested the video card and the board gave me indeed the 3beep code showing that no video display is installed, which also confirms what I've measured with the tester some weeks ago... the missing 3.3V signal. When soldering the PCB, I've also put a fuse inline with the 3.3V signal that comes from my also homemade AT-ATX adaptor (an automotive fuse holder I had lying around, it's just a test I know it's not the most appropiate setup xD), and soldered GND directly to the board input in the back of it.

The only pin I have not soldered is the 3.3V VSB, which in my board, it was not even connected to 5V, so I suppose it would have been safe, but I left it unconnected on purpose.

PD: you can also see some wires that correspond to a botched job I did in the past to repair the USB connector traces (I use USB keyboard and mouse). BE CAREFUL with that cause many of these old board do not have standard pinout for USB and you can burn something... as I did xD

Woohoo!

Very nice!

Suggest using kapton tape.

Also, look under my pcb projects in sig for pico psu adapter.

The fuse really is only needed I think for testing. Once it is shown to work you can probably remove it.

Sphere478 wrote on 2022-03-08, 09:21:

scheiss_freak wrote on 2022-03-08, 08:35:

Seems like I'm not eligible to send PMs yet. But I've set up a simple website to allow for easy ordering: https://recnas.org/

Please let me know if this is inappropriate and I'll remove the link asap.

🤷‍♂️ Dudes selling sound cards, slocket 8 adapters, dream blasters, all sorts of stuff they make here. Seems like it would be unfair to not let you do this. Seems like they don’t like people selling things unless they are making the things…?🤷‍♂️

Who sells slocket8 adapters? are there any pcbs outthere?

Sphere478 wrote on 2022-12-03, 16:43:

Suggest using kapton tape.

I second this. The adhesive on electrical tape turns gross and slimy. Kapton tape is the way to go.

LeFlash wrote on 2022-12-14, 08:58:

Sphere478 wrote on 2022-03-08, 09:21:

scheiss_freak wrote on 2022-03-08, 08:35:

Seems like I'm not eligible to send PMs yet. But I've set up a simple website to allow for easy ordering: https://recnas.org/

Please let me know if this is inappropriate and I'll remove the link asap.

🤷‍♂️ Dudes selling sound cards, slocket 8 adapters, dream blasters, all sorts of stuff they make here. Seems like it would be unfair to not let you do this. Seems like they don’t like people selling things unless they are making the things…?🤷‍♂️

Who sells slocket8 adapters? are there any pcbs outthere?

I am unsure who it was but a year or two back someone was making them

I don’t think it was oxcats. But he has some I believe unreleased 370/8 slotkets

π.0

Be sure to order as 0.6mm thick pcb

Added decoupling capacitor pads

Sphere478 wrote on 2022-12-14, 18:17:

3.3v PCI Converter pi.0.zipπ.0

Added decoupling capacitor pads

Alright you got me to try this on this ASUS TXP4. What size of decoupling cap do you recommend? 0603 or 1206?

NachtRave wrote on 2022-12-25, 05:09:

Sphere478 wrote on 2022-12-14, 18:17:

3.3v PCI Converter pi.0.zipπ.0

Added decoupling capacitor pads

Alright you got me to try this on this ASUS TXP4. What size of decoupling cap do you recommend? 0603 or 1206?

Well, you can use whatever will fit technically

You should use 0.6 pcb

I am pretty sure the 0603 will fit just fine.
0805 maybe
1206 probably not

The pins won’t stick out much if they do at all so other types may be possible as long as they don’t interfere with other pins around.

I’m not in front of the computer right now or I could make a overlay to show the sizes. And how they fit using a rectangle. If someone wants to do that and post pic what would be helpful.

Someone will probably want to do a oscilloscope test to determine optimal values. Once determined I can add values to silk. It doesn’t really matter much though as anyone ordering now could just wait for those values and use it in the meantime. Or just use it without them as others have.

The cap pad at the end for a bulk cap might be able to be a 1206

Sphere478 wrote on 2022-12-25, 15:56:

Well, you can use whatever will fit technically […]
Show full quote

NachtRave wrote on 2022-12-25, 05:09:

Sphere478 wrote on 2022-12-14, 18:17:

3.3v PCI Converter pi.0.zipπ.0

Added decoupling capacitor pads

Alright you got me to try this on this ASUS TXP4. What size of decoupling cap do you recommend? 0603 or 1206?

Well, you can use whatever will fit technically

You should use 0.6 pcb

I am pretty sure the 0603 will fit just fine.
0805 maybe
1206 probably not

The pins won’t stick out much if they do at all so other types may be possible as long as they don’t interfere with other pins around.

I’m not in front of the computer right now or I could make a overlay to show the sizes. And how they fit using a rectangle. If someone wants to do that and post pic what would be helpful.0BCDB4E5-021F-4867-87EE-B208F254D0FC.jpeg

Someone will probably want to do a oscilloscope test to determine optimal values. Once determined I can add values to silk. It doesn’t really matter much though as anyone ordering now could just wait for those values and use it in the meantime. Or just use it without them as others have.

The cap pad at the end for a bulk cap might be able to be a 1206

Yup, saw earlier in the thread about that 0.6mm height. Be sure to keep that as a note next to your zip file (all in one place so ppl dont gotta go looking around).

I am going to try with a few different sized caps and I'll report back (after I get everything - may be 2+ wks) what I see along the 3v3 line. I plan on playing around with 10uF to 220uF and seeing what the scope comes up with.

Also, the 3v3 3A 1587s are out of stock and had to order from AliExpress. I have a GeForce FX5500, cheap knockoff (rebranded FX5200 Ultra) with supposeded universal PCI voltage (two notches), that won't power on possibly due to missing 3v3 voltages across PCI. Board is an ASUS TXP4 (5v notched PCI, with NC 3v3+ connections looks like (I'll know for sure if its NC when the PCBs get here)), as mentioned, so it's the more stripped-down version of the 97. No AGP but I'll take the extra ports.

I'll get myself a variety of different 0603s to experiment with. X7A be okay you think, or do we need something special for the high-frequency stuff?

Check out the sxl2 interposer thread. Feiopa is doing some tests there that may be enlightening.

I added a note to upload post about pcb thickness.

Here are the three sizes I mentioned. the yellow rectangles should represent the actual physical size of said pieces.

I was looking into a simple DC-DC converter for something like this, namely that power card thing that made 3.3v on a PCI card for old socket 7's. I forget what thread that was in.

I found a thread where someone asked about using multiple LM2576T-5.0 in parallel here
The highlighted reply gave a few things to look for in the datasheet and I think this chip fits the bill for cheap .

The power card used an lt1083 if memory serves which can deliver up to 7.5 amps so a power card using this chip would use three chips for up to 9amps.
I did make a circuit using this chip already and it does work out to be cheap to make.

What do ye think? would this be along the right lines or is there something better out there?

-Lime

What about some diodes in series?

Sphere478 wrote on 2022-12-26, 20:18:

What about some diodes in series?

NO ! do not do it.
the voltage drop over a diode is dependent on the amount of current through the diode. They make horrible voltage droppers.

Sphere478 wrote on 2022-12-26, 20:18:

What about some diodes in series?

yeah, diode droppers are fine for something like a fan, just to drop from 12v to 11-ish to quieten it down a bit but not much more tbh

weedeewee wrote on 2022-12-26, 21:22:

Sphere478 wrote on 2022-12-26, 20:18:

What about some diodes in series?

NO ! do not do it.
the voltage drop over a diode is dependent on the amount of current through the diode. They make horrible voltage droppers.

Good to know. 😀 thanks!

I've seen them used as a way of powering a 3.3v mcu from a 5v power source, BAV99 was used I think.
I guess it worked but it is a bit hacky.

I noticed in sphere's release that he included some PSU circuits - in particular this Intel 486 Overdrive 3v3 PSU circuit. I've replicated that exact circuit and did a quick little PCB of it -- for those of you who have no 3v3 because you're on an AT-only supply (like I am). It uses the LT1587CM, which is the surface mount version, but I also included through-holes for the standard LT1587.

Anthony Zxclxiv (the guy who reverse engs the 3dfx vsa-100 chips) recommend a solution like this for these repo/cheapo PCI video cards (in additional to his mini-me VSA-100, which doesn't have on-board 3v3 and would need something like this), since it's really just about smoothing the power line for high frequency use. The variable solution for pentium CPUs does even more clever trickery (and with a whole field of SMD caps), but mostly I just wanted a simple PCB to try sphere's backplane with.

The circuit calls for a 10uF @ C1, 47uF @ C2, 22uF @ C3, 100nF 0603 @ C4, and 10nF 0603 @ C5, but you may adjust these to your specs. Also should do a 100nF decoupling cap at every slot. You can also add a diode if you want, although it's entirely optional. Add-on heat-sync required due to LDO, along with small fan depending on current draw.

Note that 3A is short of the 7A required by the PCI spec for all its ports, but is likely good enough to wire at least a slot or two. Keep power lines as short as possible. 3mm holes in corner allows you to mount on hex standoffs.

Hey. Nice little board and some good points

However those traces look a little thin for 10 watts. According to a trace thickness calculator that i use as some bit of measure, they should be around 1.4mm thick for default 1oz copper of prototype boards.

Very nice 😀

Indeed the traces are a little light.

Calamitylime’s device, I think I linked it earlier. Is good up to 20a and is buck based. So less heat

I was pondering adding a overhang to the pcb initially and having that regulator I still can but was worried about hitting thru hole devices. And opted for universal low profile instead.

As for easy power sources: atx connector or pico atx to at adapter that I made (see sig for pcb projects)