Attached are photos of the assembled unit. I'm starting off with 10 uF tantalum for Cin and Cout at the location of the VRM.

Will test and determine if I need to add some caps in the nanofarad range for Cout in the centre region. Not exactly sure what the ideal values would be, but some options for the 4x centre Cout capacitors:

a)
ceramic 10 nF
ceramic 47 nF
ceramic 100 nF
ceramic 220 nF

b)
tantalum 10 uF
ceramic 47 nF
ceramic 100 nF
tantalum 470 nF

c)
ceramic 47 nF
tantalum 150 nF
tantalum 220 nF
tantalum 330 nF

The caps on this Opteron185, for example, are all ceramics in the 47-470 nF range.

CPU needs massively low resistance equivalence for CPU's voltage core . Much less capacitor's ESR so as voltage get less.

Cheers,

pentiumspeed wrote on 2022-11-27, 01:11:

CPU needs massively low resistance equivalence for CPU's voltage core . Much less capacitor's ESR so as voltage get less.

Cheers,

What are you recommending for the centre region?

Put the power supply pins on a scope once installed and analize what frequencies you are seeing. That will determine what capacitors you should install. (I think)

Well, plug it in already! :p (but not before checking for shorts)

As for shrinking it if you say there is room I can move stuff based on your measurements but on my end it’s about as close as the boundaries say it can get. (You know better though since you have the physical unit.) but looking at the pics I wouldn’t change a thing man, it looks perfect… you sure it needs to be smaller? We’ll loose the pin one txt, yeah, it looks great…? Perfect in fact…. It’s a marvel! If it works, I think we call it done. Further contemplating on the flipping the cap idea, not necessary. Good as is.

Sphere478 wrote on 2022-11-27, 02:01:

Well, plug it in already! :p (but not before checking for shorts)

3 kids and 1 angry wife at home. I'm trying my best already. I try not to do things until all are asleeping.

I wasnt paying too much attention, but itsnt that vrm linear? those dont like lowesr and get unstable

I do believe it is linear.

Sphere478 wrote on 2022-11-27, 04:42:

I do believe it is linear.

Some may be, but it's not general for all LDOs. Datasheet should specify if there is some special requirement for output capacitor ESR...

It is a linear regulator, ultra low drop-out, MIC29302WT.

I selected it because it doesn't get hot at the maximum possible current desired and had the lowest noise of the linear units I tested. The functional diagram shows a tantalum being used on the output.

I did do some tests with a switching regulator, but didn't select it, I think because of the size requirement for the solenoid. I don't recall the specifics as that was 5 yrs ago now.

However, you are correct in that,

1This capacitor need not be an expensive low ESR type: aluminum electrolytics are adequate. In fact, extremely low ESR capacitors may contribute to instability. Tantalum capacitors are recommended for systems where fast load transient response is important.

I don't know if the ESR of the tantalum output cap I'm using is "too low". Do you? TPSC106K016R0500. The alpha photos show this 10 uF capacitor on Cin and Cout. I probably have some 10 uF ceramics that will fit. However, all the upgrade modules in my collection use linear regulators with tantalums.

Do you have any recommendations for the centre region for Cout?

says "extreme", this one is 500mohm, its fine

It seems that no one knows. Suggest trying based on overclocking results or hooking a scope and calculating what caps to use.

Plug! it! In!

Plug! it! In!

Plug! it! In!

I like to use MLCC SMD capacitors, around 10uF to 22uF for this CPU, 6.3V voltage rating too for 386 and 486 class.

Yet, the small SMD capacitors on the CPU package is minor role in your photo and is much later. The most of the ESR comes from capacitors on the that are pentium and later motherboard's.

Cheers,

Sphere478 wrote on 2022-11-27, 13:05:

hooking a scope and calculating what caps to use.

There's a measurable waveform of about 800 Hz with Vp-p of 170 mV. What size capacitor/type would you use in the centre region, and how are you calculating this?

that's pretty low frequency ripple, you should be good with some regular old 10uf bulk decoupling

feipoa wrote on 2022-11-27, 05:05:

It is a linear regulator, ultra low drop-out, MIC29302WT. Regulator-Linear_Microchip_3A_LDO_0.4V_MIC29302WT.pdf

I selected it because it doesn't get hot at the maximum possible current desired and had the lowest noise of the linear units I tested.

All linear regulators dissipate the same power in this case, it only depends in the voltage difference between input and output and the output current. So all types (in the same package) should get similar "hot". But you surely know 😉

It only has to have a low enough dropout voltage depending on the required output voltage with given input voltage at the maximum current.
Tantalums as Cout are mostly fine for these applications.
Ceramics must be used with some care because of their low ESR (regulator stabilty) and their strongly voltage dependent capacitance.

The 10uF are most probable the recommended minimum for this particular regulator. It should be fine to increase this to e.g. 47 or 100uF if necessary but this should be written in the datasheet somewhere.

Hope this helps.
Can't tell much about the 800Hz ripple from here, though.

Yeah, that’s pretty low freq.

https://www.homemade-circuits.com/calculating … acitor-for/amp/

Maybe this helps?

Btw, to those reading this in the future, what feiopa is seeing is potentially something specific to his system. Yours may have a different interference frequency from the parts you used to build your system. Best guess is this is coming from his psu. So it is possible the best capacitor config may vary system to system.

Feiopa, you could also try different psus.

The center caps are a added feature. We don’t need to worry about them much yet. Plug it in, see if it works 😀

ChrisK: I have definitely observed a good variance in how hot different linear regulators get under identical load conditions.

You got to give me some time here. It is difficult juggling family life and hardware on the weekend, at least for my situation. I cannot do squat while the household is awake. If I try, I'm driving away every 20 seconds, or I can hear my wife yelling louder and louder until I show up, even if she is not calling me directly.

I plan on trying a variety of PSU's. The 800 Hz may even be my crummy scope. 800 Hz is awfully close to the 1 KHz reference option it employs.

The unit is functional, but I'm trying to get more MHz out of it, and this is why I'm focusing on the seemingly unimportant 200 mV waveform. If someone has a cap. value to recommend for an 800 Hz ripple, it would speed things up some.

If I read that right gals/guys, it sounds like he just told us that it works!

WOOHOO!

feipoa wrote on 2022-11-27, 22:26:

The unit is functional, but I'm trying to get more MHz out of it

I knew it LMAO

Keeping poor sphere in the dark all along

Sphere is abused :’(

Report circle/sphere abuse, 1 (800) 314 1592

See something, say something.

Wonder how many mhz he got it to, hopefully it’s doing better than the other adapters. Fingers crossed.