Notices by Andrew Zonenberg (azonenberg@ioc.exchange)

@becomethewaifu @ada This piece was inspired by a bunch of inner layer PCB rework I was doing at the time. The board layout is based on a real design that I never finished, but I had a screenshot handy to show to the artist.

If you're familiar with underground utility locate markings, at least in the US, you'll see I spent quite a while making the site prep accurate :)

@becomethewaifu @ada If you like those, you'll probably like this series I commissioned.

Different artist (Usanekorin from Collateral Damage Studios in Singapore) but heavily inspired by Shapoco's work.

@foone have you ever had a problem where your first impulse was NOT "Oh, I know, I'll make a keyboard to solve this"?

@f4grx You'd have to make it differential via a buffer, balun, whatever. The SFF spec has the requirements for power and differential amplitude.

As far as what the lower bandwidth cutoff is, I'm not sure. They are AC coupled and the coupling caps are on the module.

Probably easy enough to just make a breakout, pick up some cheap SFPs, and characterize?

@f4grx The bandwidth of the AGC, coupling cap cutoff frequency, etc. will vary with the type of SFP.

You might have better luck with e.g. 100base-FX SFPs than 10Gbase-SR ones.

@f4grx @benjojo @jaseg PPP / HDLC over 57600 baud UART over fiber? :P

@mei @mwk It's not like FTDI is immune to bugs themselves. Do you know how many steppings of the FT232H were made? It's horrifying.

I wanna say the currently shipping 2232/4232H die is A13.

@gorplop @gsuberland These are the ones I use
https://xplosafe.com/peroxide-testing/

@gorplop @gsuberland There might be more to it because I don't remember hearing about ketones being spontaneous peroxide formers (maybe it's only the mix of IPA + acetone that causes the reaction and not pure acetone?)

I'm not an organic chemist, I just know it can happen and how to test for it. Test strips are cheap, when in doubt I just do the entire solvent inventory and if I accidentally test a non-peroxide-former boo hoo I wasted a $0.50 test strip.

@gorplop @gsuberland Secondary alcohols in general are peroxide formers. It's not a fast process (the bottle in question was nearly empty and close to a decade old, frequently opened to use a few ml so there was always fresh O2 in the headspace - basically a worst case scenario WRT reaction speed) and you are unlikely to get enough in the stock bottle to e.g. blow up when the bottle is opened.

But you can definitely accumulate enough to be a risk if you were to distill to dryness or something.

I could be wrong but I think IPA is first oxidized to acetone, then oxidized more to form TATP?

@Dtl A *liter*???

That has to be one of the dumbest ideas out there. There are so many more stable secondary explosives out there if you really want to mess around with energetics. There is no reason whatsoever to make primary explosives - especially ones that sensitive - in such quantity.

@szakib @Dtl A primary is one that can be easily set off by mechanical impact, heat, etc. These are inherently much more dangerous to handle for obvious reasons.

A secondary is one that is sufficiently insensitive that it is difficult or impossible to make it go boom without something else exploding next to it to provide simultaneous high heat and pressure from the shock wave. These are relatively safe to handle - some of them can even be ignited with a match and will burn vigorously but not detonate - but can't be used on their own because you can't set them off directly.

Most real world blasting and munitions use a small charge of primary explosive in a blasting cap or similar to then set off the main charge of secondary. Sometimes, for a particularly insensitive main charge, you might even have a "booster" of intermediate sensitivity between the two.

The idea is that the main charge can be handled in near complete safety until you insert the detonator, and a mishandling of just the detonator might lead to a blown eardrum or loss of a finger or something but won't leave a giant crater The mating of the two is the riskiest part of the operation as a screwup there could set off the main charge, but this is a short window of time which can be performed with the utmost care.

@szakib @Dtl Organic peroxides in general are easy to make, highly sensitive primary explosives.

A bit too easy, to the point that every once in a while you hear about accidents in a lab from a particularly unstable solvent (diethyl ether comes to mind) oxidizing spontaneously in storage then going boom when heated during a distillation, left in storage and crystallized in bottle cap threads, etc.

This is why the most peroxide-prone solvents are often mixed with various stabilizers to reduce the rate of peroxide formation, and labs will buy small containers (so they don't sit around too long) and mark the bottle with the date they were opened and periodically test peroxide levels. This way they can be discarded before dangerous concentrations build up.

@szakib @Dtl TATP is an infamously sensitive primary explosive, to the point that it can go off on its own from random vibrations and such.

Terrorists call it "mother of satan" because it's a great way to end up in whatever afterlife you believe in before you've reached your target or even fully assembled your IED.

@gsuberland @szakib @Dtl @funranium Does that say 1969 on it???

/Me ducks behind nearest concrete structure

@gsuberland @szakib @Dtl @funranium Yeah I read the whole post. Phil finds the craziest things.

Worst I've had to deal with over the years...

A bag of unlabelled gray powder that turned out to be something inert but was scary until we knew, given the previous lab user's love of energetics

A bottle of IPA that was old enough it measured 400ppm on a peroxide test strip

Some concentrated nitric acid that sat around long enough to weaken the cap so it disintegrated into dust when someone tried to open it

My worst spill, a bottle of NaOH based PCB photoresist developer that had sat around long enough that the plastic had gone super brittle. When I picked it up during a cleanout trying to turn it around and see the label, it split open at the seam and got all over the floor, my glove, and a few drops on my pant leg.

@foone guess my brain is weird too.

At one point I was thinking of getting car license plate 55 8B EC.

But decide not to because I'd want 8B E5 5D C3 on the rear plate if I did that.

@foone For what, i386?

CD 1A

@mntmn .net binary? 32 vs 64 bit mismatch?

@foone But... if you are transitioning in the *other* direction...

Does that count as reballing?