Before I dig too far into this, some personal anecdotes.
Back in the day, I decided to experiment with liquid cooled computing. Y’all know the score, much talk about Cray and Flourinert, and a couple of hobby things with water cooling closed circuit style.
Lots of talk, lots of speculation, but no real meat and potatoes.
So, I had a socket 754 Intel lying around having just upgraded, time to play.
After much research I found that “mineral oil” was the thing to go for, for the home hobbyist / experimenter, so where to get it? Eventually I found a place to buy “liquid paraffin”, which is the same thing by a different name, it’s a horse laxative, and you can buy it in gallon cans for not a lot of money.
This stuff is good because it is reasonably viscous, clear, not very hygroscopic, and quite hard to ignite.
So I proceeded to find an old (glass, not acrylic, for thermal transfer and dissipation) fish tank, and set about cutting bits of acrylic to carry everything, and also stripped EVERYTHING down to bare bones, PSU the lot.
I decided to be really clever, and use a pair of WD Raptors (these were fucking expensive back in the day) striped for speed, and cooled by the oil, but out of contact with it, by way of sitting them in some ziplok bags, and yes, I tested the bags for 72 hours first to see if they would degrade.
Now, no well done experiment is a failure, because they all lead to valid and useful data, and such was the case here.
What really killed this experiment was the oil wicking up the insides of the SATA 
cables, osmosis style, out of the oil and back down again to the SATA connectors in the HD’s and thence to the inside of the HD’s, which of course killed em, stone fucking dead.
It took 10 days to wick in, but it got there in the end.
However, there were quite a few other interesting “discoveries”
1/ It was genuinely, truly, totally fucking silent.
2/ It did not necessarily cool the PC better, but it cooled it more evenly, eg the range of temperatures across the mainboard were all within a degree or so of each other.
3/ It weighs a lot more than you think.
4/ Note the 120mm fan, yes, fans do work in oil, just slower, and pure convection alone wasn’t nearly as optimal as sticking a fan in there to stir it up.
5/ note also the fans on CPU and northbridge, same story.
6/ In an air cooled PC the coolant “leaks” everywhere, but since it is air it don’t matter, in this one the coolant leaked everywhere too, hence the containment vessel of the fish tank… the big difference is the thermal mass of the contained coolant, this thing would take 30 minutes of gaming to even nudge the overall coolant temp.. I experimented first with 4 x 150 watt aquarium heaters BTW.
7/ You really, really, really need a fixed and stable build, hardware wise, it’s hard to describe the mess when you try to pull one component or add some RAM etc…. once it is lagged in oil you DARE not put any power on it after you pull it, and thin layer of oil is a great insulator.
8/ Add some LED’s, and one word, “Aurac” from Blakes 7, woot…
Prior to this you ended up running air cooled, and if you ran rack mount kit, particularly 1U kit, that meant lots of noisy little 40 mm fans running in harmonic like bombers engines, this shit on the right was in the hallway, and you could hear it all over the house.
But ultimately, this back-story is just that, it is a back-story to highlight what it means to indulge in Personal Computing.
Nowadays world and dog can go out and buy a Raspberry Pi, , its the modern equivalent of those 100 electronic experiments peg board toys you used to get, which were 10 different ways to wire up a bell, 10 different ways to wire up a light, and … no… no op amp, 555 timer, or anything else, so everyone who bought the fucking thing is going to do the same “experiments”
I know, I’ll go and buy a 3d extrusion printer, and download the same skull file everyone else does, the same iphone cover everyone else does, the same naked woman everyone else does.
It’s not PERSONAL.
The big problem with this is that unless you get to play with something, you don’t get to learn… I made a living for a year or two in the sweet spot between discovering that 99% of laptop batteries contained 18650 li-on cells, and all you needed was them and a charge regulating circuit and the “fuse” chip, all of which I could get from china cheap and fresh, and after-market batteries becoming a mainstream business… an option that was only possible because I could play, which is something you can only do with YOUR property.
YOU never own an iphone or ipad, it is “sold” to you under licence.
Now we are even going away from that, cloud compute is all about using some remote CPU power, so your device doesn’t need any, some remote storage, so your device doesn’t etc… and you really can’t play with something that is 75 millisecond ping away somewhere, who knows where…
This part has been delayed a week, because I have ummed and aahed about this next bit.
Amongst the other junk I have in my workshop are a couple of ex UK MOD EHT sources, they came out of the back of big radar sets, 12 VDC current limited to an amp or two in and a nice fat spark at the rate of 5 to 7 a second out that will jump a 5 mm air gap with ease, so we are probably looking at around 10 KV minimum.
I got these and a dozen big 3 farad 350 V caps for an experiment.
A couple of years ago a guy I know is around, we start playing, we discuss this, I say yes, the voltages are *similar* to a piezo kitchen gas igniter, but if it goes to your finger while the gas igniter will make you yelp and then it will pass, with these babies it will really fucking hurt, and it will still hurt 24 hours later too, much more current (I have had this argument before too, coil or electronic ignition vs a magneto) so don’t ask me why but we got to zapping some various old bits of electronics, and it turning into junk.
He decides he wants a EHT generator.
I tell him plasma globes have the same sort of thing, (but much less powerful) just break it apart, throw away the globe and the base, you’ll get a tiny PCB and the EHT wand and a 12 V supply jack.
Couple of days later he has made this thing up, he shows it to me, 8 x AA cells and a bunch of self amalgamating tape and an old marigold glove and he has a portable zapper.
I have no idea why, maybe it is just me, but it never occurred to me to question WHY he wanted this, and it was only later that I recalled saying “oh yes, won’t make a difference” and proceeded to demonstrate that applying the EHT to the end of a CAT5 cable, with the other end 10 metres away plugged into some crappy old D link 4 port home switch, was still instant death to the D link.
Only later being after (I can talk about this now) I heard that the ISP he worked at lost a whole rack of switches and routers, basically half their infrastructure.
No obvious reason why either, the whole lot just didn’t do what it should, some boxes power cycled endlessly, some powered up but did nothing, some didn’t power up, none of them worked, and of course the server room was sealed, and he didn’t have a key, but he did have access to the other end of the CAT5 that went into one port one ONE of these switches….
This is not an isolated incident, I know, but can’t prove, of at least a dozen other incidents of this scale, all different people and places, it’s the dirty little secret, JEDEC vramp and uramp, silicon chips and proms and fpga etc are all hideously susceptible to high voltages, and if you limit the current there are no visual clues whatsoever.
I only discovered this by accidentally meeting a guy called Tom, I needed an electronics whizz for a project, I found Tom, Tom made a steady living potting two female RS232 sockets in a short piece of poly pipe, of course inside the poly pipe and potting was an opto-isolator.
So periodically someone new stumbles across this dirty little secret, and decides to have some mischief, or revenge, or just plain I wonder what will happen if,,, oh shit… and because almost nobody experiments any more, nobody but the likes of me has any inkling what is going on when a bit of expensive electronics suddenly stops working or starts acting very strangely.
Now I personally know of at least two people who have used this method to circumvent what we can call “reluctant” “cough” Seagate “cough” warranty departments, who would accept a DOA return, but not something with an intermittent fault, or which worked, but nowhere near where it was supposed to.
It is anecdotal and a rumour, but I was told of one northern uk police department where an orifice accidentally discharged his taser getting into the car, the barbs went into the wiring loom under the dash / footwell, and took out *everything* not just the onboard computers and digital video, but the vehicle electronics as well.
The point that I am trying to address here, is that the lack of Personal Computing removes the opportunity from everyone to learn anything of any depth greater than what icon to hit with what gesture to open an app, and this includes those who end up designing, building, maintaining and working with this kit.
Everything has a switch mode PSU now, which is a *very* flexible piece of kit, gone are the days (in countries with a 220 VAC mains supply) of causing much hilarity and issuance of magic smoke by turning off a co-workers PC at the wall, putting the switch on the back of the PSU to 110, and sitting back and waiting.
But the flexibility of the switch mode PSU and its ability to “eat” almost anything has also led to the creation of a whole new breed of UPS’s and inverters that put out modified sine wave, where modified means it looks like a set of escher stairs, it’s got fuck all to do with sine waves.
Because I love you guys, and I am a generally fluffy and cool guy, I just went out back, pulled a brand new DC power supply from a brand new in the box 500 quid cisco router with 12 VDC in, and look what you see.
(Yes, I know it looks like AC, but it is really just the ripple on DC)
0.2 V per div, and three pics taken about a second apart, not only is there AC ripple, it is quite significant, and variable, ranging from around 0.6 V to 1.0 V, there is also a significant amount of higher order transient noise, you can SEE where the DC rectification is being done badly by cheap components, that themselves rely on some sort of capacitance and tolerance in the input stage of the device being powered.
Yes, it’s a shitty old single trace 40 MHz Hitachi, but it still works, and it is light years ahead of “no scope and relying on the label on the device in question”
Now I’m not an electronics guy, but to me, if I was telling an electronics guy to build me a 12 VDC PSU for a 500 quid router, and he produced that, the cunt would be looking for a new job.
I’d expect 12 VDC plus or minus 0.12 V, which is only 1% tolerance, and I’d expect fuck all ripple, which is only a couple of 50 cent caps in the PSU output stage… which would also prevent start up spike and shit.
Now, with all of the above, I am not suggesting that ordinary commercial kit should be able to withstand the direct application of 10 KV, but I am suggesting that only a fucking lunatic would interconnect a rack containing upwards of 100k worth of kit with CAT5, which is an ELECTRICAL conductor first and foremost, and not say to themselves, hmmm, this means that anything that hits anything in this rack is going to hit everything in this rack, I might wanna take some precautions here…
220 or 110 volts AC would have done as good a job as the EHT, it would just have left evidence, magic smoke and burnt tracks and tripped breakers. Hell I can remember seeing articles about in in dead tree magazines, cat 5 and RJ 11 and coax all wired to mains sockets and called variations of “modem buster” etc.
Personal Computing is then the difference between knowing various bits and pieces of biology and medicine and first aid, and having an app on your iphone to take your pulse.
Personal computing is the difference between owning and maintaining and driving your own car, or calling the cab company, and not actually knowing if you are being taken on the quickest and most direct route… you see, there are always follow on bits of ignorance that lead from initial bits of ignorance… give up the role of driver, you give up the role of navigator too…
Computing has become such a fundamental and intricate part of every day life, that a lack of personal computing of necessity means being ignorant of much of every day life.
It simply is not possible for you to grasp or understand most of it.
High Frequency Trading, you have no hope of understanding what it REALLY is, unless you have prior knowledge of the old racket where the mob used to get the horse race results from a town 500 miles away before the bookies did… hell there was even a good film about a guy who did it in Australia, can’t remember what it is called now.
If you, reading this, could see all those pictures and knew what they depicted without the need for captions, and if you could follow everything discussed here without the need to google it, then you are blessed my son, and I’ll wager, you are someone who has direct experience of Personal Computing.
If you had difficulty, then I will wager you have no direct experience of Personal Computing, just Computing, with your sealed for life, non customisable, as it comes from the factory, tamper proof, sold under licence only, computing device.
And as computing is inherent to modern life, that should scare you… lots.
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In closing, EHT is no fucking joke, any spark is an arc, and any arc is a conductor, if you happen to create a current path via an arc to some powerful source, eg 440 VAC, the consequences could be not merely painful or expensive but fatal.
If you want to play with EHT, at the very least always keep your feet insulated from ground, and one hand in your pocket, preferably your favourite hand.
If you want to zap things with EHT, see the first point above, disconnect them from ALL power sources first, and all further electrical connections and interconnects.
