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Tubes! And undervolting in general...

A project log for Random Ridiculosities and Experiments

Sometimes yah's just gots tah try somethin', regardless of whether it'll become a full-fledged "project"...

eric-hertzEric Hertz 05/30/2022 at 12:404 Comments

Found this in drafts, several weeks later...

This *might* qualify as procrastination, being that I can't justify doing the projects I want to do, due to projects that need to be done, but for which I haven't the energy, so instead of doing either, I'm taking "short" breaks to "clear my mind," or maybe more realistically to "get my mind going in the project-direction"... but, which wind-up not being so short at all, and are instead sending me off in new ventures into project-imaginings....

OOOF.

I admit, I'm human... just as prone to such "distractions" as anyone.

But, if we take these distractions out of the picture, we're still left with the fact of spiralling subprojects making ultimate goals ever further-out.

"The original goal" (which is to say, the last goalpost I can recall having set, without spending hours trying to recall the one before it) was to get a reliable x86 system running. Which led to batteries. Ugh. That was weeks, and still *barely* resolved. But just about the time I almost had that solved, I wound-up depleting my "workshop battery" while trying to run simulations for the former. 

So, the quick solution for that would've been to jumper-cable it to my alternator and charge 'er up! Sure, could throw a can of soup in front of the heater-vent and do a bunch of other things at the same time, maybe lay back and watch a flick on the ol' 28inch bigscreen!

But in the meantime gas prices have quite literally doubled in a handful of months, now nearly double the highest I've ever seen, FAR FAR surpassing inflation, just like far too many things these days.

And ain't it ironic that I spent my whole friggin' adult life without having even gotten a license, perfectly content with bussing and having a tiny carbon footprint... until I was quite literally faced with the choice of either living in a van, this van, this gas-guzzling van, being the only option for shelter I could afford, or face sleeping in cardboard boxes.

So, because some pretend-greenhorn who cares more about funding other countries than giving jobs to our own people allegedly thinks gas is the worst thing there is for the environment, I've got to figure out how to use coal, or kill birds, interfere with their migratory-patterns, or figure out how to dispose of worn-to-inefficiency football-field-sized carbon-fiber turbine-blades, or destroy salmon runs, or deal with spent Uranium, or deal with batteries which are notorious for burning down buildings, or so many other "greener" solutions... (I can say this because I was once "green").

Where was I?

Oh yeah...

So, now I need to recharge my "workshop battery" to continue working on whatever project it was that I've long nearly-forgotten, that whatever it was was kinda darn-near essential to my being who I am... Oh, right... A friggin' computer. HAH!

Right, so, once I resolve the "workshop battery" charging-scenario, then I can not only resume that project, but *also* use that same resolution to *power* it, once it's complete.

Right!

So, progress there halted to make way toward later progress there. 

And I think I've come to that same conclusion about so many things with so many setbacks now that I've LONG forgotten what the original goal was, and many have been long-abandoned (was propagation of my genes ever in there?).

....

Right.

Where was I going with this?

I've been working for weeks on a suitable battery charger. YES. At this point I could've bought a dozen ready-to-use if I'da been paid minimum wage for the time I've spent on it. But I'm almost there, Just One More Day, REALLY!

OH YEAH, and I got sidetracked again by a mechanical disaster which I'm pretty sure, but not certain (no one has the heart nor balls to say) few folk in their right mind would not drop everything to have fixed immediately rather than keep pressing their luck on shoddy theories they've convinced themselves of, based on basically zero actual experience in the field... I mean, it looks BAD to me. And so far the best I've heard to a "been there, done that" was "well, we do what we have to to limp back to town." But, being that all the symptoms diminished immediately after I did a minor adjustment, symptoms which I've dealt with for Five Years, my guess is I've been on that limp back to town since day-one... And that minor adjustment made for smoother rides than I've ever known, so I've kinda been doing part-time trying to work myself up to fixing that and going back to the charging problem...

OOOF. Where was I?

BOTH are EXHAUSTING, and only *slightly* related to things I'm "good at" (if I'm good at anything, these days).

So, I've taken to distractions hoping they'll be motivating...

(Well, you have to understand that weather plays a huge part in all this, as well... and here the weather is even more octo-polar than I).

...

RIGHT!

So, I discovered A Video Series About Using Vacuum Tubes, at *reasonable* voltages!!!!

Holy crud, I had no idea.

I haven't yet gotten to the part where he builds a computer out of tubes.

....

And I'd long-forgotten why I started writing this until I saved the draft to get that link, then saw the title I wrote... Right...

.

UnderVolting.

.

Part of *BOTH* my charger-endeavor AND my x86-powering endeavor has actually come around to this on several occasions in the past months.

Say you need a diode that drops 0.5V at 2A... Where do you turn?

The obvious solution is Shotkey... Right?

Maybe not!

What if you have a high-current 20A TO-220 rectifying diode, rated at 600V sitting on an old TV's PCB?

Sure, look up them specs, and you'll find a forward-voltage nearing 2V. But That's At 20A!

You'll be lucky to find specs at 2A, but it may just turn out to be *exactly* the low-voltage, better'n Shotkey at 2A solution you need. Seriously.

Similar for MOSFETS.

If you're not concerned about space, you might have what you need in some ancient old PCB you'da thunk couldn't possibly have come from an era capable of such. Nah, they just packaged and rated them differently!

...

So, Strangely, the idea of UnderVolting tubes never really occurred to me as viable; I figured those high voltages were necessary to get those electrons flying. But, Usagi shows otherwise, and suddenly, especially after my recurring Diode/MOSFET discoveries, it makes a heck of a lot of sense.

Tubes' cathodes can emit something like a measly 30mA worth of electrons. That ain't much. (Unless you consider where those electrons come from, or where they have to go... then it seems downright amazing! Or) UNLESS you use Really High Voltages. No wonder they use speaker-matching transformers on old stereos.

BUT, if you're just trying to do some simple binary logic, 20mA is plenty, probably excessive, to feed the next stage. And, suddenly, something once so daunting as vacuum tube voltages can be brought down to a few 9V batteries!

(Distracted much? I've got a GNARLY wheel bearing to replace!)

...

It's now June 11th. I replaced the terifying wheel-bearing, thankfully, but it may need some adjustment, and I can't get the blasted dust cap on. Slather on the grease for now, think about that pop bottle that fits perfectly and duct-tape. Try Try Try to build up the energy to have another go at it.

...

I got as far in Usagi's Vacuum Tube Computer to see just how many tubes are necessary for 8 bytes of RAM, and my brain locked back into #Incandescent RAM. I now have a 4-bit refresher! And am unable to get my mind off it... 8 Bytes, And i'mma hook it up to a Z80, I guess... Because, well, for some reason I'm fascinated by the idea of using a regular memory-access instruction to access physical hardware that may take *seconds* to respond (holding WAIT, all the while)... I dunno, I mean, I could write a program that runs on Incandescent lightbulbs for its only RAM, running at some two or three instructions per second, *in C!* Hahahahaha!

Never did get around to charging my workshop battery. Really, that's kinda just as ridiculous; the nearest outlet is several hundred-foot extension cords away, and as I mentioned, the weather is octopolar, so I'd either have to invest in numerous extension cords, or make an umbrella (and a dolly?) for it. Of course solar's not a horrible idea, but $$$, yahknow... And it's not like I can just leave it set up for days on end. Though, as long as I've put this off, the battery probably would be fully-charged by now even if I'da just bout $20 worth of panels pumping out less than an amp whenever I opened the storage-unit. But then, of course, the next question is where do i store them? There's not a flat surface left in there, horizontal nor vertical. Heh! Money has been so tight for so long, the idea of spending even fifty bucks a month for twice the space is hard to wrap my head around. Now with gas so high, it seems even less feasible. But, realistically, it may actually be equalled in savings, driving less, possibly electricity nearer, being less subject to weather. I probably just have to wrap my head around it, and my head doesn't do that sorta thing easily. It's barely off #Incandescent RAM, as I write this.

Discussions

Paul McClay wrote 06/18/2022 at 08:26 point

I read all of that. Just saying.

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Eric Hertz wrote 06/18/2022 at 10:20 point

Wow, Thank you(?)

BTW, I can't believe I never thought to use the rotary tool with CD/DVD slides... #CDCNC 

Genius.

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Paul McClay wrote 06/19/2022 at 06:12 point

Yer welcome :)  and thanks.

It looks like you did gather a respectable collection of lore supporting CD/DVD mechanism re-use when you were active with that. I haven't touched the laser diodes at all yet.

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Eric Hertz wrote 06/20/2022 at 04:57 point

I was really doubtful they'd (laser diodes from DVD burners) be powerful enough to *do* anything... but I was pleasantly surprised. Still, nothing like what a rotary tool can do.

I should go link that over there!

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