LeoDJ

LeoDJ, 12 days ago

Here is a demo video showing the #USB2Speakon in use.
I'm not sure if the camera microphone captures it accurately, but it's surprisingly loud :D
(I expected around "room volume" at most)

Build log thread coming soon™

A video showing the test setup of the last picture of the previous post, but in action. There is nothing else connected to the speakers other than the USB2Speakon and laptop.

LeoDJ, 12 days ago

insert standard run-of-the-mill #PCB assembly steps here
Paste, place, reflow the one side.
Solder the other side by hand (because I didn't have a hot-air station at home and was impatient).

#USB2Speakon

Solder paste application under the microscope. I think this is my best application yet.
Placed the components on the top side
Bottom side part soldered by hand. If in doubt use more flux!

LeoDJ, 2 months ago

Finally, all parts arrived today!

Time for assembly.

LeoDJ, 2 months ago

insert standard run-of-the-mill PCB assembly steps here
Paste, place, reflow. Paste, place, reflow. Solder the rest of the components manually.

It went pretty normal, although the assembly order of the straddle-mount USB-C connector needed a bit of thought ^^
I ended up with this procedure:

• Reflow the top side without the connector
• Place it after the paste of the bottom side and put flux on the top side contacts
• Reflow bottom side with hot air

#DongleHiderPlus

PCB on a hotplate, reflowing
The finished PCB with the donge-to-be-connected beside it
The finished PCB with everything assembled

LeoDJ, 2 months ago

And with that, the #DongleHiderPlus is done!

It features room for 2-3 skinned dongles while still providing an external USB A 3 port.

I tested it and it works like a charm* !
The receiver and different USB 2 and even USB 3 devices worked on the first attempt.

Massive props to @frameworkcomputer for making the whole development process very easy, with all needed information already public and even supplying a base 3D-printing-ready #ExpansionCard model.

#Framework16 #FrameworkLaptop

The finished expansion card installed in my Framework 16 Laptop
A USB tree view of an internal Logitech Unifying dongle and externally plugged in USB 2.0 stick
A USB tree view of an internal Logitech Unifying dongle and externally plugged in USB 3 card reader

LeoDJ, 3 months ago

@gsuberland @patagona
A more traced out version of the connector PCB image can be found here:
https://github.com/patagonaa/isdt-cm1620/blob/main/RevEng/Hardware/ISDT%20CM1620%20Connector%20Board.png

LeoDJ, 3 months ago

@jaseg
I'd like to, but dedicated chips for "5S LiPo voltage to EPR source" (ideally up to 240W) don't seem to exist yet, according to my research

LeoDJ, 4 months ago

During soldering of the 65W modules, I noticed that our heat sink concept worked almost too well xD
It was really hard to solder to the power pads of the modules. Even if you heated it with a good soldering iron for over a minute, the other side of the solder joint was barely liquid.
As soon as you took the iron away, the solder solidified instantly.
And the enamel of the copper wire had to burn off too under those conditions, making it even more difficult.

#PDBrick #usbC #usbPD

The modules finally soldered. Took only a bit over an hour xD
The modules still being uniformly hot (38°C) minutes after soldering. Indicating quite good thermal conductivity.

LeoDJ, 4 months ago

After mounting the 100W modules to an aluminum strip, it was time to test the array.
We didn't have enough 100W capable loads to do a long full-load test, but close enough :D
The thermals look promising. The aluminum strip spreads the heat pretty well and got to around 60°C itself.
The hottest spot on the modules is now the USB port interlock P-FET at 90°C. And that will improve with airflow too.

#PDBrick #usbC #usbPD

Thermal image of the 100W modules. The middle two power banks were already full, but the outer two modules have finally reached an equilibrium. 90°C at the P-FET and the aluminum strip got to about 60°C (measured via a piece of electrical tape)
Thermal picture of the whole test setup.

LeoDJ, 4 months ago

The 65W modules got tested too.
They stay surprisingly cool. After some time at full load it only reached around 50°C.

And it looks like the thermal solutions works exactly like intended.
As you can see in the thermal video, the modules beside the loaded one heat up noticably too (in comparison to the rows below, which you basically can't see at all, thermally)

#PDBrick #usbC #usbPD

video/mp4

LeoDJ, 4 months ago

During final assembly of the array, the 100W module group suddenly showed a short circuit on the input.
I was puzzled at first, but had a hunch.
And sure enough, the 1mm thermal pad was slightly too thin and the main input ceramic capacitor punched through the thermal pad and shorted out against the aluminum strip.
Luckily it didn't crack ^^"
I fixed it by simply putting another layer of thermal pad on top :D

#PDBrick #usbC #usbPD

The imprints left in the thermal pad

LeoDJ, 4 months ago

The housing of the #PDBrick is a piece of rectangular aluminum extrusion.
For mounting the server PSUs I decided to design and 3D-print some plastic rails, so the PSUs can be slotted in.
The DIY PSU backplane will get fixed to the front rails too, so the alignment and mechanical forces of the PSUs being slotted in will be manageable.

#usbC #usbPD

CAD drawing of the rails

LeoDJ, 4 months ago

To connect two server power supplies in series, the PE reference of the secondary has to be severed for the high-side PSU.
On those HP DPS units, that's pretty easy. You have to open it, file down two metal spacers a bit, put insulating washers between PCB and case and replace the metal with nylon screws.
This only removes the connection between output GND and PE. The metal case remains grounded and the floating output is still referenced to PE through the low-side PSU.

#PDBrick

LeoDJ, 4 months ago

As time began to run out, I quickly threw together the backplane PCB using perfboard, thick copper wire strands and lots of solder. It has to potentially handle up to 100A.
And yes, the wonky speed holes are necessary for improved airflow :P
With the added resistors and bridges, the PSUs turn on and everything works.

Wiring the backplane to the modules was a bit frustrating, because of the thick diameters, thermal mass and tight spacing, but worked out fine.

#PDBrick

A multimeter connected to the backplane PCB showing 24.67V. Everything is working as intended.
The 65W modules all wired up to the backplane, the cables to the 100W module backplane are already prepared too.
The 100W modules are connected now too.

LeoDJ, 4 months ago

After a final test of the electronics, everything can be put together.
@techbeard drilled and countersunk the necessary holes in the aluminum extrusion and fabricated some corner pieces, so the back plate can be screwed to the extrusion.
We mounted the rails, backplane and #usbPD module array inside the extrusion. Now the PSUs can be slotted in, which is quite satisfying.

#PDBrick

The last PSU being slotted into the aluminum extrusion with a satisfying

LeoDJ, 4 months ago

The 230V wiring consists of a #powerCON #TRUE1 socket to two IEC plugs. We had to remove the jacket, because it would've been too tight otherwise.
The aluminum casing is grounded via the good connection between PSU casing and aluminum. (see above)

You might also notice the #XT60 plug. It's a generic 24V output for connecting external devices like LiPo chargers etc.
The main reason for its existance is still having "left-over" power budget from the power supplies (~600W) :D

#PDBrick

LeoDJ, 4 months ago

Once it was used for a longer period, we noticed the aluminum extrusion being pretty warm to the touch (~40°C).
Apparently, the server PSUs use around 40W during idle. But when drawing that amount from the output, the power usage doesn't go up that much, so they seem to be burning it internally when having (almost) no load?

Also, maybe the aluminum could be a few degrees colder when painted? Because bare aluminum doesn't seem to radiate much heat.
Or we'll install additional fans.

#PDBrick

LeoDJ, 4 months ago

As the server PSUs feature #SMBus connectivity, we planned to display some metadata on an OLED.

I soldered up a small perfboard with a buck converter, #ESP32 and a few connectors.

The ESP32 only communicates with the low-side PSU, as I didn't want to implement isolated I²C.
But I noticed that the values coming from the PSU were pretty hit & miss anyways. Especially during light loads.
So I simply used the values that matched the actual values closest and doubled them.

#PDBrick

ESP32 plugged into the headers on the PCB
Back side of the PCB, insulated with Kapton tape
Debug view of the values coming from the PSU displayed on the OLED (In/Out Volts, Amps. Temperatures, Fan RPM)

LeoDJ, 4 months ago

That's all for now.

I also threw everything in a Github repo here: https://github.com/RainbowLabsDE/PDBrick
(No claim for completeness or instructions ^^")

LeoDJ, 4 months ago

@wonka @techbeard
Maybe. When modules become available and cheap enough. But that'll probably happen in 1-2 years at the earliest.