@tubetime This is horrifying. 🤢 In eng school we once had a guest lecture from a crewed submersible design engineer. I forget the exact numbers, but by convention they would overdesign metal hulls by e.g. 10x; but for any transparent ports they would overdesign them by e.g. 20x because they knew that much less about the material behavior...

@tubetime
This thread has strong vibes of "let's build a submarine in our backyard" to it.
(I have only an AA in engineering, but I'm sitting here going "WTaF" at just about everything. And that AA did include properties of materials, a *lab class*.)

@tubetime
Check this out. You can clearly see the hatch just laying there like it popped right off the sub. Who could have guessed?

https://youtu.be/eEThkm0Dih8

i've unfolded the cells now so they lay flat. i have to weld the two positive terminals (on the red wire, somewhat out of focus). the other little thing hanging free is the thermistor.

first, i took it apart and documented the process here on iFixit: https://www.ifixit.com/Teardown/IBM+Thinkpad+700C+Battery+Pack+Teardown/176472

you can read through that if you want and come back. but basically that tells you how to remove the lid without making a huge mess.

@tubetime <scroll scroll scroll>

YOU DIDN'T SHOW US YOUR BATTERY WELDER!!!! 😭

first, since i always seem to do stuff the hard way, i designed a board from scratch for the 2350. i call it the Rotten Pi 2350[A] mostly because i threw it together in a huge hurry two weeks ago.

@tubetime My cathode ray oscilloscope from the 80s has that functionality built-in. It's very useful.

@tubetime Usually zener diodes have a much steeper curve than that on the positive side. Not sure what type that one is.

@tubetime Please take good care of these jewels.

@tubetime now what to build with them all. 🤔

@tubetime I am curious to know if you have some Signetics 2519 shift registers in that collection? There are a few Apple 1 enthusiasts who would be interested (including myself).

@tubetime I preferred the Gravis Ultrasand MAX myself

@tubetime
@foone

It will totally blow away your Sound Blaster...

@tubetime I heard it was fully 16-grit

@tubetime Defect? Or is it a "feature"?!?

@tubetime I would say RSVP that ROM, but I’ve seen you do harder hacks to recover data from chips before.

@tubetime Boo!

@tubetime Jelly! Always enjoy seeing your pictures from these. Are there any other flea markets in other locations in Oct?

@tubetime I need to get one of those metal j-poles again, I gave mine away when I moved cross county and regret it!

@tubetime I wish I lived within driving distance of this. It is probably good that I don't.

Thank you for the pictures

@whitequark Amazing

@whitequark can't like this enough

@whitequark wow that's pretty good, I once designed an entire computer in 2020 and completely forgot about it.

@tubetime perhaps it knows something you don't about your other printers!

@tubetime The alt text says "notably absent from any dialog is the option to "select printer" - that is because the printer is selected after the click on "print"

@tubetime for me it helped to configure the wanted printer as default in the settings of my OS

doing it again right now! tune in!

@tubetime this, I gotta see...

@tubetime Those cells are similar in size to an 18650? That's a chonky battery pack!

@tubetime Ah, the illusion of choice! When experimenting for EMC testing recently (and then reading the spec more carefully), I found that on any recent (type-C) design that decision is already made for you. GND and shield are connected within the cable plug:

@tubetime Directly to the ground plane. I've never failed EMC/ESD with that.

Inductor is the worst option, I've fixed a few EMC fails where folks did that. Essentially an HF open. I want to keep the signals going through the cable in the cable which requires an HF short. Open makes an antenna driven my any common mode current in the other wires.

Capacitor or cap || resistor has a use in breaking low frequency ground loops, keeping extraneous DC currents out of the braid. Not relevant for USB.

@tubetime All the EMC people I talked to said directly to GND. And it's now even mentioned in the USB-C spec.

And @jacqueline passed EMC with it so another great data point.

@tubetime I love how it subtly implies that you *might* be done after 15 disks.

@tubetime I loved OS/2 I ran warp (red) on a pentium pc.. in the 90's in my private quest to avoid as much as possible Microsoft.....

@tubetime

Man that progress bar is *peak* 90’s.

@tubetime I have never worked on a device with peripherals on I2C where I2C wasn't a source of misery.

That many hardware designers enthusiastically put multiple I2C devices on a single bus and sometimes get cute with one or more level shifters or other bonus hazards feels like definitive proof that they hate firmware engineers and are actively trying to destroy us.

@tubetime

I used to be in contract manufacturing of maximum-reliability electronics. Cut traces happen more than you think.

In our case (pick one) (not exhaustive):

1. The client made a change and we had older boards.

2. Experience in the field necessitated a circuit modification, but changing the board design would mean going through gov't approvals again.

3. Different configurations of the same product would get different traces cut rather than making seperate boards for each model.

@tubetime resistance is futile 😅

@tubetime "layers"? what are "layers"?

hahahha

i'm starting with a design from an NXP app note. https://www.nxp.com/docs/en/user-guide/UM10992.pdf (see page 15)

@tubetime is .. the orientation of the F actually significant? In my early (2010) PCB days on the yahoo PCB group, DJ Delorie made vias out of actual rivets. Which Google can no longer find, but this is similar https://youtu.be/CvO5JaOkEXI?si=bE7Fc3oXGlHPFFp_

@tubetime I never had the opportunity to get up close and personal with any IBM 729 tape drives, but used plenty of IBM 3420 drives as well as the 3480 cartridge drives. And my day is going fine, thanks for asking :blobcat:

@tubetime I love that place. Glad you got to go too.

@tubetime sir, there is a yeti skiing on the tv behind you. 😁