Mastodawn

✧✦Catherine✦✧

pov: you wake up to receive a package with a vacuum chamber and discover that the vendor is a crackhead and a menace to society

this is a vacuum chamber. the power supply that comes with it has a type-C connector and it puts 12V on Vbus unconditionally. the pump works off both 5V and 12V, so it can pull vacuum off a normal type-C power supply. but the solenoid release valve (that lets you open the chamber once you're done) requires their illegal type-C-shaped power supply. also, not only does the chamber not support PD negotiation, it does not even have a CC pulldown.

to add insult to injury, it's using a NEMA 1-15P plug.

✧✦Catherine✦✧Feb 28

it has been [ 0 ] days since i was at risk of utterly annihilating some device by plugging the wrong type-C cord into it

anyway, Glasgow revD0 will have input protection against over-voltage to ensure that this scenario cannot happen to you

mnl mnl mnl mnl mnl Feb 28

@whitequark serious f* these guys, same here…

@whitequark It's mindboggling that USB C is somehow cheaper(?) than a barrel jack.

✧✦Catherine✦✧Feb 28

@snowfox I don't even know why they chose to build it this way. I think they wanted a right angle connector and right angle barrel jacks are pretty rare?..

Jernej Simončič �Feb 28

@whitequark @snowfox Does the device work with regular USB-C power supply (as in negotiates 12 V)? I remember seeing an almost identical thing a year or two ago, where the device did negotiate, but shipped with same kind of power supply.

✧✦Catherine✦✧Feb 28

@jernej__s @snowfox it extremely does not and I checked it

✧✦Catherine✦✧Feb 28

@jernej__s @snowfox double-checked and it doesn't even have a CC pull resistor

EndlessMason Feb 28

@whitequark @jernej__s @snowfox
I'm an abolitionist but you should call the cops

✧✦Catherine✦✧Feb 28

@EndlessMason @jernej__s @snowfox I'm an abolitionist too which is why I will disassemble it and replace the circuitry with a 12 V PD trigger

EndlessMason Feb 28

@whitequark @jernej__s @snowfox
Restorative maintenance

@whitequark They don't seem any rarer than RA USB C (which I don't think I've come across); searching for "12v power supply" gets https://www.aliexpress.com/item/1005007264933490.html which has a RA connector as one of the options pictured.

I think it's common on some laptops?

Netzteil Adapter 220V AC DC 5V 6V 8V 9V 10V 12V 13V 15V 24V Universal Ladegerät 1A 2A 3A 5A 6A 8A 10A EU UNS Für LED Treiber - AliExpress 13

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aliexpress.

Ridley @ WATCH LYCORECO Feb 28

@whitequark I once had a sheet music stand light that was like this for reasons I cannot fathom, except the power supply was USB-A (at 12V) and it came with an A->C cable

✧✦Catherine✦✧Feb 28

@rcombs yeah this is why I check the ratings on every single power supply I unbox

@whitequark My "NOT USB" label has people asking a lot of questions already answered by the label

@whitequark the engineer misunderstood USB power delivery

@JennyFluff @whitequark Ahhh!

neocat_googly_shocked

Christian Berger DECT 2763 Feb 28

@JennyFluff @whitequark Engineers understanding USB power delivery typically stop doing engineering.

Trammell Hudson Feb 28

@whitequark I haven't seen USB-C abused that way yet, although I do have a collection of USB Mini plugs that are weird, like this debug POST card that has RS-232 levels on it.

Jakob (Jack/Jackie)Feb 28

@th @whitequark aruba uses Micro-B for RS232 on their APs (or UART level serial? Not sure)

Brent Cook Feb 28

@jakob @th @whitequark saw that mini USB RS232 hack a few times on PMC boards too

James Tinmouth Mar 1

@jakob @th @whitequark IIRC it's not proper RS232 levels as it needs more hardware too. Boneheaded idea tbh, even with the little exclamation mark on the port.

Luke Wren Feb 28

@whitequark Reminds me of my projector which has a 3.5 mm TRS audio output next to a 3.5 mm TRS 12 V DC output

✧✦Catherine✦✧Feb 28

@wren6991 aaaaaaaa

✧✦Catherine✦✧Feb 28

@wren6991 chaotic evil

Luke Wren Feb 28

@whitequark They saved a BoM line so arguably lawful evil

Luke Wren Mar 3

@whitequark photo for proof now that I'm back home. The brand is Optoma. Great projector, designed by crackheads

✧✦Catherine✦✧Mar 3

@wren6991 would you like to have a guest post on crackhead.technology

Steve Syfuhs Mar 3

@wren6991 @whitequark what the fuck

theking killed the radio star Feb 28

@whitequark i have a stir plate that uses usb c with a fixed 9v
its cursed and it worry about it :p

groff 🇺🇦Feb 28

But the EU said everything had to have a USB connector.

✧✦Catherine✦✧Feb 28

@geoffl this is not a USB connector. this is a USB-shaped connector. there's a big difference

Rob Ricci Feb 28

@whitequark @geoffl I have a device that delivers 12v power via a 2.5mm audio connector and I wonder what audiophile hurt this person

a kilo of saucepans (rakslice)Feb 28

@ricci @whitequark @geoffl radio shack, I assume :P

RootWyrm 🇺🇦

@ricci @whitequark @geoffl man, I got you all beat.

You are faced with a PC that has two cards with 4 RJ45 ports on them. Surely that's quad ethernet, right?

NOPE!
2 ports of 100baseT with bypass.
And 8 ports of RS232 running at 15V!

Extremely expensive hilarity ensues.

✧✦Catherine✦✧Feb 28

@rootwyrm @ricci @geoffl I hope you just had to swap transformers?

(also, bypass?)

@whitequark @rootwyrm @ricci @geoffl Ethernet with some relays inside so you can physically bridge the two ports.

@whitequark @rootwyrm @ricci @geoffl ooooh the special ethernet bridge thingies!

basically it can operate relays to allow ports to be looped through (if, say, the equipment is malfunctioning) or the OS can do software filtering/selective forwarding if it's working

Andrew Zonenberg Feb 28

@rootwyrm @ricci @whitequark @geoffl Cisco RS232 is very much a thing, quite common in networking gear.

But if properly designed it and Ethernet can be mated nondestructively. Passive PoE probably not. But regular Ethernet shouldn't hurt RS232 and vice versa if actually spec compliant design.

Rob Ricci Feb 28

@azonenberg @rootwyrm @whitequark @geoffl We used to operate several hundred RJ45 RS232 ports, much easier to wire (this was for server serial ports before proper out of band management was a thing)

Rob Ricci Feb 28

@azonenberg @rootwyrm @whitequark @geoffl

Ceci n'est pas une Ethernet

Chris Siebenmann Mar 1

@ricci @azonenberg @rootwyrm @whitequark @geoffl It us. We still have ~130 servers with console serial ports wired up this way in our machine rooms, all of them using network cables and plugged into what look to an innocent, hurried eye like network switches¹ (at the top of racks, along with the real switches). Fortunately we use a different color for them than any of our other network cables.

¹ Digiport Etherlites, which do somewhat cursed things to transport serial over Ethernet.

@cks @ricci @azonenberg @rootwyrm @whitequark @geoffl for extra spice, one can carry Avocent KVM over identical RJ45

Andrew Zonenberg Mar 1

@vmp_ @cks @ricci @rootwyrm @whitequark @geoffl I have also seen full speed USB over... i can't remember if it was rj11 or rj45 but it was literally vbus/ground/d+/d- crimped onto four connector pins

Chris Siebenmann Mar 1

@azonenberg @vmp_ @ricci @rootwyrm @whitequark @geoffl There's also USB over network cable extenders that are probably doing a bit more than that since their length limit goes up substantially.

(We bought one once for potentially sticking USB temperature sensors into a different room than the server that was reading them. In the end we decided it was better to pay more money for real temperature monitoring modules. (I work in a university, we DIY a lot of stuff sometimes.))

Andrew Zonenberg Feb 28

@ricci @rootwyrm @whitequark @geoffl yep i use out of band serial for last ditch debug on a bunch of stuff

Andrew Zonenberg Feb 28

@rootwyrm @ricci @whitequark @geoffl (they won't talk, of course. but it should not cause permanent damage to either partner)

RootWyrm 🇺🇦

@azonenberg @ricci @whitequark @geoffl oh, you sweet summer child, the 100bT with bypass should have been your first hint.

When you dump 15 volts from 4+ sources into an early 100bT *hub*, good things do not result.

When you dump 15 volts into a 100bT hub *AND* your 3640's Ethernet port instead of it's console port, TAC is not amused.

When you dump 15 volts into the PRI interfaces, they do not care. Till you're sending on pins 7 and 8. Then they care a *LOT*.

Κέχ (👻🏴‍☠️)Mar 1

@rootwyrm @azonenberg @ricci @whitequark @geoffl What curséd magnetics-free shit are we talking about here? I've only been doing networking since 1997, but can't recall seeing any likely candidates. Everything I can recall would've been fine with the amount of current your typical MAX232/knockoff can swing with its adorables little charge pump.

✧✦Catherine✦✧Mar 1

@xek @rootwyrm @azonenberg @ricci @geoffl isn't MAX232 capable of sourcing like 50 mA+ of current through that dinky little charge pump somehow? or am I misremembering?

Κέχ (👻🏴‍☠️)Mar 1

@whitequark @rootwyrm @azonenberg @ricci @geoffl TI's datasheet says ±10mA, and the voltage/load-Z graph in Fig 5-1 makes me think that's being generous. (SLLS047N, p5, "5.6 Electrical Characteristics, Driver" and p6 Fig 5-1)

I suppose there's ~15µC of charge on the caps that could be dumped all at once when you plug a cable?

But, I dunno, I've swapped Fast Ethernet and console cables plenty of times without any problems. Aside from my life being slightly shorter due to the stress of not having a recent enough backup of the configuration for business-critical gear which has gone totally non-responsive.

✧✦Catherine✦✧Mar 1

@xek @rootwyrm @azonenberg @ricci @geoffl thanks, I misremembered then

RootWyrm 🇺🇦

@xek @whitequark @azonenberg @ricci @geoffl yeah, you're not even close. These were literally custom made cards that were nothing like what you've ever seen. Designed by a maniac. It's been 30 years, but I remember some details.

PCI 2.1, with a Molex for both 12V *and* additional 5V. They were absolutely massive. I don't remember the exact part, but the new version would be TL16C2752.

That configurable trigger level is about to get very important.

RootWyrm 🇺🇦

@xek @whitequark @azonenberg @ricci @geoffl if you're unfamiliar with PCI, there is a 256 byte configuration register space. These cards used the configuration register space to set the output. These cards defaulted to 'full send' if uninitialized.

I don't know or remember any of those ICs, but I remember the enormous tantalums and several parts under heatsinks.

It was theoretically capable of 200ft+ RS232 links on Cat3. You can do that math. Neat, right?

Except when the cable is 4.5 feet.

RootWyrm 🇺🇦

@xek @whitequark @azonenberg @ricci @geoffl but it was fine, right? Surely it can't get more insane!

It had LOTS of configurability so it could work with any nightmare fuel, like DCD vs DTR. And it had smarts for dealing with things like low returns.
As long as it was initialized. And didn't get confused.

Ethernet, for example, was very confusing to it, it's disturbingly large capacitors, and it turned out wholly insufficient separation and protection!

Ignas Kiela Feb 28

@geoffl @whitequark technically it's only mandatory for stuff that deals with radio signals (and then it has to comply with a subset of USB-C and USB PD)

✧✦Catherine✦✧Feb 28

@ignaloidas @geoffl wait, that is how they defined it?!

Ignas Kiela Feb 28

@whitequark @geoffl yeah, it's pushed into some radio-related regulation because it was easier to do it from the legislative side lmao

the standard is technically some ISO thing but it's just a subset of USB specs