@jaseg@chaos.social
@jaseg@chaos.social avatar

jaseg

@jaseg@chaos.social

I am doing #electronics, #embedded programming, #python scripting, hardware security and recently some sewing. Pronouns: er/they

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gsuberland, (edited ) to random
@gsuberland@chaos.social avatar

excuse me WHAT

JLC are doing five 8L boards for... ONE POUND AND SIXTY PENCE

jaseg,
@jaseg@chaos.social avatar

@gsuberland Capped vias are free on 4L/6L at the moment too. I guess they have some investment money to spend again, this time on aggressively going after their higher-end competition.

gsuberland, to random
@gsuberland@chaos.social avatar

if you flip the ESD hazard symbol upside down it becomes a "no italian hand gestures" sign

jaseg,
@jaseg@chaos.social avatar

@gsuberland Is that the one from KiCad? It has a few extra fingers.

yngmar, to Electronics
@yngmar@social.tchncs.de avatar

LED lightbulb autopsy. All the LED chips are cracked. The lamp still flickered and sometimes worked steadily and they were not getting hot from use, merely slightly warm.

All the cracks start from where the chips have been soldered, so I think the cracking might've been caused by being soldered too hot/too long.

LED chip macro photo of another chip. Two cracks enter the chip from opposite sides, starting from the edge of the soldering joints. One is on the opposite end of the solder joint in this case.
LED chip macro photo, third chip. One deep crack beginning near the end of one solder joint and entering into the center of the chip.

jaseg,
@jaseg@chaos.social avatar

@yngmar Could also be due to thermal expansion and contraction of the PCB substrate slowly tearing the LEDs apart while their packages get more brittle with age.

jacqueline, to random
@jacqueline@chaos.social avatar

check this shit out https://www.youtube.com/watch?v=IfUVvQnAvcI

jaseg,
@jaseg@chaos.social avatar

@jacqueline I looked into the stuff a while ago. IIRC you need one of their higher-end machines to print it. In the end I didn't manage to source a cassette of it at a reasonable price though, so I wasn't able to try it on my H-500 handheld consumer printer.

jaseg, to random
@jaseg@chaos.social avatar

This place has such a different vibe at 3am UTC compared to 3pm UTC

attie, to random
@attie@chaos.social avatar

Schematics are a form of communication... So communicate!

There's nothing worse than a mystery box, with signals going in, and signals coming out... and no explanation.

Being forced to reach for the datasheet, when you're trying to understand a schematic is bad. Avoid it.

A screenshot showing the bridge IC itself, with the LVDS waveform and its slots. Each position is labelled with the associated output of the bridge IC.

jaseg,
@jaseg@chaos.social avatar

@attie Yesssss!

If only CAD tools were better at drawing though 😅

emf, to random
@emf@emfcamp.org avatar

You have until 2pm tomorrow to order a Tildagon badge - after that, we can't guarantee that there will be any more available until 2026!

Order your badge here: https://www.emfcamp.org/tickets/badge

This badge will be reusable at the next EMF and beyond. You can read more about our new approach to badges on the blog: https://blog.emfcamp.org/2024/03/18/tildagon/

jaseg,
@jaseg@chaos.social avatar

@emf Tbh, I think comitting to re-using that thing is a good call.

I've always found it pretty awful how we normalized it as a hacker community to give out big piles of throw-away electronics, with all the labor, materials and embodied energy that goes into them, just for 99% of them to never be used past the few days of the event.

jaseg,
@jaseg@chaos.social avatar

@emf Also, nice choice with the SFP connectors for the expansion boards.

jaseg,
@jaseg@chaos.social avatar

@emf (I don't have a problem with people making their own badges for fun, as an art form, I just don't like the event giving away thousands of them to people who don't want or need them)

jacqueline, to random
@jacqueline@chaos.social avatar

hey electronics heads. anyone got any tiny little project recs that use bga components? seems like a good soldering skill to pick up, but i've no head what to put together to learn!

jaseg,
@jaseg@chaos.social avatar

@jacqueline How about a breakout board for this little chip, could be useful if one ever needs just a bunch of voltages for biasing stuff:

https://www.lcsc.com/product-detail/Power-Management-Specialized-PMIC_WILLSEMI-Will-Semicon-WL2868C-20-TR_C2941884.html

jaseg,
@jaseg@chaos.social avatar

@whitequark @jacqueline Oh god, I remember looking at that thing and being like "wat" when I saw the sheer density of that PCB.

jaseg,
@jaseg@chaos.social avatar

@23n27 @whitequark @jacqueline gotta have a controlled-impedance board for signal integrity at the 300 kBd baud rates of those CC lines /s

overflo, to random
@overflo@23.social avatar

dieser ca 3x8mm grosse stecker ist die zugangsregulierung im metalab.
Er ist defekt.

jaseg,
@jaseg@chaos.social avatar

@nblr @marble @overflo Und auch das hier: https://www.heise.de/news/Urteil-Schwachstellen-Hinweis-auf-Produkt-Webseite-reicht-nicht-9685101.html

davidho, to random
@davidho@mastodon.world avatar

TIL there’s something called the sea bunny.

jaseg,
@jaseg@chaos.social avatar

@IcooIey That's so cool!

ajuvo, to random German
@ajuvo@chaos.social avatar

Fingerabdrucksperre reicht nicht

https://netzpolitik.org/2023/gerichtsbeschluss-polizei-darf-fingerabdruecke-nehmen-um-handy-zu-entsperren/

jaseg,
@jaseg@chaos.social avatar

@Cyb3rrunn3r @ajuvo Auf einem modernen Gerät mit funktionierendem secure element wie z.B. einem iPhone reicht auch ein kurzer, 4-6-Stelliger numerischer Pincode.

jaseg,
@jaseg@chaos.social avatar

@Cyb3rrunn3r @ajuvo Kann sein, dass ich dich missverstehe, aber ich finde schon, dass auf einem iPhone ein 4-6-Stelliger Pincode hinreichend sicher ist, da durch die secure enclave in Hardware sichergestellt wird, dass angreifende nur 3-5 Eingabeversuche haben. Bei einer zufällig gewählten 4-Stelligen numerischen Pin entspricht das für angreifende einer Erfolgschance von weniger als 1%.

jaseg,
@jaseg@chaos.social avatar

@Cyb3rrunn3r @ajuvo Ein guter englischsprachiger Artikel mit mehr Hintergrund: https://words.filippo.io/dispatches/secure-elements/

jaseg, to Electronics
@jaseg@chaos.social avatar

I just found an interesting genre of weird but potentially useful chip: System support PMICs for large SoCs such as BD71805 (2$, i.MX SoCs), RK809 (2$, Rockchip SoCs) or WL2868 (50ct, Omnivison SoCs). These chips provide between 7 and around a dozen DC/DC or LDO channels with digitally configurable voltage(!) through I2C, battery charge measurement, and configurable power-on sequencing. Some even have fun bonus features such as an RTC, or a built-in audio codec(?!).

jaseg,
@jaseg@chaos.social avatar

All of them seem to be reasonably well-documented, so when you need like, half a dozen power rails for something, they look like a good option even stand-alone, with just a small micro instead of a full SoC next to them. I guess there's probably also Linux kernel drivers floating around for these that could be useful as a reference.

jaseg,
@jaseg@chaos.social avatar

In particular the WL2868 seems fun: It has 7 LDOs with I2C-configurable output voltages at decent currents, and costs about the same as any other single LDO. It does come in a pain in the ass WLCSP with .35mm ball pitch though, so filled and capped vias are a must for that one.

jaseg,
@jaseg@chaos.social avatar

Datasheet links:
BD71805: https://www.lcsc.com/datasheet/lcsc_datasheet_1912111437_ROHM-Semicon-BD71805MWV-SE2_C337992.pdf

RK809: https://rockchip.fr/RK809%20datasheet%20V1.01.pdf

WL2868C: https://www.omnivision-group.com/file/product/files/WL2868C-V1.4.pdf

jaseg,
@jaseg@chaos.social avatar

@projectgus Neat! And that one is cheap too, at ~1.30$ and comes in a fairly reasonable QFN package.

jaseg,
@jaseg@chaos.social avatar

@projectgus If anything, I'd think an SoC like that would have worse load behavior than something I cobble together with much lower operating frequency components. I suspect the biggest difference to a standalone LDO with these would be poorer analog performance, in particular poor output noise and PSRR specs as these aren't that important for SoCs.

jaseg,
@jaseg@chaos.social avatar

@projectgus The WL2868 I mentioned above would be an exception from that though. Since it's meant for camera sensors, it has several LDOs spec'ed with very good PSRR and decent noise specs.

whitequark, to random
@whitequark@mastodon.social avatar

@gsuberland if you light up a LED (cheap, recent green LED... InGaN or something probably?) and then turn it off by connecting both terminals to GND, how long does it take from that point to when it no longer emits appreciable amounts of light?

jaseg,
@jaseg@chaos.social avatar

@gsuberland @whitequark There's a bunch of effects that add up to a (light emitting) diode's reverse recovery behavior. There's multiple mechanisms for carrier recombination including photon and heat emission, and there's the physical transition of carriers across the junction expressed in the diode's transit time. Which ones dominate depends on the diode's design. For LEDs, I've only seen carrier recombination cited as the limiting factor.

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