Progress Report:

All the components should arrive today, for Yo-Duh's circuit.

I'll still be missing the connectors, but I want to get this array up and running first.:p


Anyone know how I can test the output of this array? I'm talking about a load that'll draw up to 120 amps at 5 volts:shrug: :eek: 36 amps on the +12 line, and 90 amps on the +3.3 (by itself, of course, since 5 and 3.3 run together!)


Also, does anyone have a source for shims for TO-220s, to isolate them electrically from a heatsink?

You can't buy the shim material from the same place you bought the chips?

As for a load, peltiers should work. You can calculate their resistance knowing the amps they draw at their spec'd voltage, and then you can calculate the amps they will pull at whatever voltage you give them. I have a few old 72W'ers around here that I use for creating loads like that. At 12V you will need to put a HSF on the hot side to prevent damage to the pelt, at 5V or less you can just hold it in your hand and feel either slightly warm or slightly cool depending where you hold it.

No, Digi-Key only has thermal pads, and I got some, but I need the ring that isolates the screws electrically from the heatsinks.

:shrug:

Oh well, it's not a big deal, but it would be nice. I was hoping for some additional safety, because the heatsinks are large (easy to slip up with a screwdriver):
http://www.allelectronics.com/images...arge/HS-89.jpg

(Max heatload would be 6.4 Watts)

I'm working on putting it all together today.


I also load tested the PSU, with a 1 ohm resistor (actually 2 * 2 Ohms in parallel, 10 Watts each) on the +5 line, as well as the 10 Ohm resistor (25 W) on the +12 line.

Results:

+5v:
no load: 5.22v
w/ load: 5.04v

+12v:
no load: 11.68v
w/ load: 11.87v


The resistors get very toasty, very fast! If anyone tries this, I'd recomend either to keep it short, or get a resistor that's got a very high wattage. Mounting this onto a small PCB will help a lot, and use heatshrinks!


I also test mounted the heatsinks, and using a 6-32 3/8" screw, a nylon washer and a nut, the heatsink is so far electrically isolated. Anodizing...

I found a mounting solution, from an old thread:

http://smt-adapter.com/perl/part.pl/...O-D3-SMT-S.htm

Nice, simple, easy and clean!

Thanks to this good site.


[edit: now don't ya'll hate posts that don't seem to have anything to do with anything? This'll make sense, once Yo_Duh's article is posted!]

Some more results:

PSU#2:
+5 no load: 5.26v
+5 w/ load: 4.99v

+12 no load: 11.51v
+12 w/ load: 11.87v


PSU#3:
+5 no load: 5.19v
+5 w/ load: 4.98v

+12 no load: 11.72v
+12 w/ load: 11.85v


PSU#4:
+5 no load: 5.22v
+5 w/ load: 4.99v

+12 no load: 11.64v
+12 w/ load: 11.86v

I've got a bunch of pics to post, 7 in all.

#1: A closeup of one of the chips inside the PSU: the ML4824CP-1 (the older pic was sharper)

#2: closeup of the F E101

#3: closeup of the ST 1141A:

(reprise)

#4 closeup of the F A036B

#5 the big heatsink (5mm thick Alu)

#6 the smaller heatsink (3.5 mm thick)

#7 the heatsink height (~8.0 mm)

I almost forgot: here's the load tester!

I also hook up 2xAOpen 300W PSUs to power my PC.
I have no problem running them together.

Before installation, I adjusted the pots of +3.3, +5V rails to be at the same level first. Then join the green and black wires of each PSU together to have it start together. I then joined only +3.3, +5, and +12V lines from the other PSU and dummy load +5VSB using a 10 Ohm 5W resistor.

Yes, but by doing so, you defeat the output coil (the big one that's got 3-4 turns), and you add ripple to the output lines.

I don't suppose you have access to an oscilloscope to measure it?:(

i don't have much technical knowledge.

just monitor the volt flucuation from BIOS and MBM (but not much flucuation anyway)

Well, I suppose that it won't hurt, but you really should read Punisher's post on Page #2.

Directly wiring ATX PSUs together is really not recommended. It may take away some of the safety features, as well as creating havoc to one another.

On the other hand, you probably don't want to do what I'm doing, and just buy a big PSU: it'll be cheaper.

good luck with your project!

i learnt to use 2 PSUs from overclockers.com forum
btw, i also use a UPS with power conditioner. i hope that also helps reducing the ripple.

Some progress, and a Q?


The circuit is coming together nicely. Yo_Duh and I resolved some last minute issues.

I had a difficulty with the power up sequence, but with a set of AND and OR gates, I can route a "Power Good" signal to the mobo, if no less than 2 PSUs are on. The signal is TTL compatible.

The mobo supplies 4 mA to the PWR ON line of the PSU, to turn it on, so it'll have to put out 12 mA, to power up all three.

What I'm not sure how to deal with, is the +5V Stand-By line.

Q: how much power does a mobo need from the +5 Vsb line?

...and how do I route enough power to it, not knowing which PSU will be available?

The PSU is rated for MAX 1.0 amp on the +5 Vsb line, so I assume that the mobo requirement is quite low, but what's it for?

I think it is for the WOL and sleep functions. Other than that, I have no clue...

Given that the 1 amp output rating is due to the regulator, (LM7805 or the like), I think I'm going to assume that the power draw is very minimal, and maybe TTL level-like.

I figure that, beyond WOL, it probably triggers the PSUs ON, when the power button is used. It might also drive an LED on the mobo.

So now I need to figure out how to route +5 Vsb to the mobo, without knowing which PSU it'll come from.

Option 1: make the first PSU of the array a requirement. It would provide +5 Vsb (as well as -5V and -12V, if I find that they're needed). This would simplify decoding the "power good" lines, as PSU1 must be ON, as well as either PSU2 or PSU3 (one AND and one OR gate).

Option 2: Use the 3 +5Vsb lines as TTL inputs, and devise a circuit that'll output a TTL level signal, hoping it'll be powerful enough.

Option 3: use a Yo_duh style circuit to merge the three lines. A relatively expensive solution.


Ok, I'm going to go with #1: it's obviously the easiest, safest, and simplest solution.


In the mean time, I measured the area within my case, to see how it's all going to fit. These PSUs are built in such a way that modifying them to be slimer would require a lot of work, so that part is out. Watercooling however, is still a possibility (but will be delayed indefinitely).

Within my case, I have 6 * 5 1/4 bays, and 2 * 3 1/2 bays. If I remove the 3 1/2 tray, and leave only one 5 1/4 bay available, all three PSUs will fit (PSU height: 3 3/8". Total height: 10 1/8").

So much for a DVD drive. Goodbye floppy. Where am I gonna fit the temp probe displays?!? (hack time :D )

The PSUs are just a tad wider than a CD-ROM (by about 1/8"), so I'll have to bang up the case's innards a little bit. Drive rails can still be used, I think... I'll need to tap screw holes to the PSU sides.

The last thing I need to do now, is figure out how to route the AC power to each unit. Since the PSUs are turned around, the AC inlet is facing the front of the case. I also need to add a power switch to each one, as well as a couple of status LEDs.

The original plan was to use panel mounted multipin connectors, through which *everything* would be routed. I don't have those connectors yet, and I don't have a built frame for it right now.


Yo_Duh's circuit assembly is coming along nicely. I also started to build the pump relay switch, and finished assembling the revised airtrap.


That's the weekend report!

The 5Vsb is used for a number of things, of which I believe all are optional (optional for you depending how you want to use it, PSU's in gerenal are required to have it to give the user the option)

Wake-On-Lan
Wake-On-Ring
Wake-On-PS2 (eg. power-button on your keyboard)
Wake-On-USB (again, power-on from USB keyboard, keep your optical mouse LED on while comp is off)

If you don't want any of these things, then you don't need to provide 5Vsb at all IMHO. Also, look in your MB documentation and you will likely find a few jumpers for things like whether USB should use 5V or 5Vsb. Depending on the amount of current you are designing this to allow over 5Vsb you may want to change some of those jumpers.

If this was a real server MB, the management processor would also run off 5Vsb, and the current required would likely be a lot higher.

BB, you might want to check Mouser's website for products made by Amphenol, Bourns, or DGS. The last two specialize in 5-15R solutions (5-15R's are the standard staggered 3-pin power connectors on the back of a standard PSU [sometimes called IEC 320 connectors]) On average, they'll hold up to around 15A@230v, and you can get them with screw terminals or solder lugs. I'm thinking one or two 'panel mount' style IEC320's drilled into the back of your case, with short run IEC320 cords (w/RFI filters of course) inside the case going to each PS. Now, as far as Amphenol, take a look at their 97 series. You'll want to go with one of their connectors that supports 'Size 12' pins, cause size 12's can handle ~23A a piece. If you're still running 4 PSU's, try one of the Series 97 20-15 receptacle/plug combos, should run you about $45 US w/o the cords to run from wall to receptacle, and plug to PSU's. Kinda pricey, but I personally think while being the better of the two options from a saftey standpoint, it would also be pretty cool looking to plug your comp in with a 1 1/4" wide connector with a screw lip ;)