CanadaPlus
@CanadaPlus@lemmy.sdf.org
- Comment on For crying in the sink, stop posting imgur links 2 hours ago:
It’d be kind of weird if anyone on SDF doesn’t know how to run a VPN, anyway.
- Comment on thank you 1 day ago:
Dope!
- Comment on Researchers Discover the Optimal Way To Optimize 1 day ago:
To give some detail they didn’t, they designed an algorithm that’s as good as possible using the specific approach they used. I was all excited someone had finally designed a provably polynomial pivot rule. This is a more modest step forwards, and depends among other things on a small amount of random noise being added to the problem.
- Comment on KIDPIX 5 days ago:
I remember it from good times in the early grades, and from the time I misclicked it in later grades during some pretty serious assignment and it fucking screamed through the lab, haha.
- Comment on KIDPIX 5 days ago:
Yes, it definitely still wasn’t on the school computers a decade later. /s
- Comment on Is there some sort of "underground" net for old computing? 2 weeks ago:
Sounds dumb. /s
- Comment on Image uploads aren't working again 4 weeks ago:
Did they come back at some point since your last post?
- Comment on What is there to know about magnetic storage mediums? 4 weeks ago:
Hmm, all the way up at 1mm. Man, that tape length really adds up, doesn’t it? So, to the question exaclty as I asked it, I guess obviously yes.
If I’m also building the head, the dielectric gap that does the reading and writing can probably be as small as tens of microns, since you can fairly easily make an edge that fine. Keeping the tape clean and even enough to not crash would be hard in that context, though, since it seems like clearance needs to be on a similar magnitude. Does anybody know what consumer tape reader/recorders use?
In tape form getting an even layer of medium might also be challenging, although if I went with a disk instead it could be spin-coated. Highly oriented particles sound doable with a bit of chemistry.
I’d upvote this, but ironically it would make it look like I didn’t upvote it.
- Comment on What is there to know about magnetic storage mediums? 4 weeks ago:
Wow, exactly the kind of thing I was looking for posted in 3 minutes. Amazing!
It goes into pretty poor detail on the actual medium itself, unfortunately. How fine were the particles? What was the exact recipe that worked?
Some of the commenters had much more interesting things to say:
@verdatum
> As a kid, the thing that blew me away was Tim Hunkin’s The Secret Life of Machines. He had an episode on the cassette player/recorder where his partner demonstrated that cassette tape could be emulated by taking Scotch tape patting it into a or iron-oxide and running that result over the tape heads. “This is the sound of my voice recorded on sticky-tape and rust.” that revelation absolutely blew my child mind. :::: ::: spoiler @DerWahreTee >I might be able to give you some advise here. I am a material chemist and I professionally work on polymer coatings similar to the one your using. I think your problem is at least partially a poor particle distribution and uneven coating thickness. The particulate you are trying to suspend needs to have a particle size <1mikrometer. When you buy such particles as a dry poor they have agglomerated during the drying process I.e. they have become stuck together in unevenly sized chunks. This creates also makes the particles less evenly spread throughout your coating than it visually appears. To break up these agglomerates you actually need a tremendous amount of kinetic energy which your magnetic stirrer can not do. Also the Mayer-bar isn’t really the ideal method to apply your coating even if you can’t see it it is notoriously uneven on a microscopic level especially when applied by hand. Ideally you would use a spincoater which could apply you coating more evenly. Hope this helps
@fiscap
Commercially produced floppy disks go through a magnetic alignment process, while the coating is still wet. I think the magnetic particles in your solution/suspension are too random to produce a consistent and reliable flux transition during the write process. If you do try this again, try to figure out a process to align the particle orientation and keep it in place until the coating fully cures.
@stamasd8500
> I am pretty sure the magnetic material that you used is part of the problem. You don’t give a lot of detail on what exactly you used, but in the video you say “black iron oxide” so I infer you used magnetite, Fe3O4. That is not the correct material to use. I did some research not long ago into magnetic materials used in the period, and even recreated some magnetic material after poring through some research papers and patents from the 1950s to 70s. The magnetic material used on floppy disks is a type II or III material (as defined for magnetic tapes) so either a cobalt-doped gamma-Fe2O3 or a chromium dioxide-based material. Magnetite is not correct as it doesn’t have the required saturation flux and coercivity. I have in fact recreated in my basement lab a type II material, a cobalt-doped gamma-Fe2O3 ferrite which would be appropriate for that. It’s not difficult but it requires patience and precision. And a few tools, including an electric oven that can go to at least 850 degrees Celsius.
The last one gives me one possible place to search next. What are the numbered material types referenced?
Anyway, if it weren’t for the sponsor, the way to make the substrate would have been just a punch, right?
- Submitted 4 weeks ago to retrocomputing@lemmy.sdf.org | 4 comments
- Comment on 4 weeks ago:
So that’s 20 Hz? Lol. That is like a baloney slicer.
I suppose, even though they had the technology to make a much faster platter, they way they were using disk storage at the time probably made seek time not an issue. The alternative would have been spooling through a tape for a while.
- Comment on 4 weeks ago:
They did without the grotesque luxury of lower case letters.
- Comment on 4 weeks ago:
I mean, I’m sure cost saving on labour were noticed as well. And that’s not a bad thing. I, for one, am pro-flying shuttle loom.
- Comment on 4 weeks ago:
How else are they supposed to program with handheld bar magnets? /s
- Comment on What would have to happen to make everybody realize we weren't exaggerating when we said Trump would be like Hitler? 5 weeks ago:
You go further, people don’t necessarily know how oblivious America is either, and go more by romanticised Hollywood tropes about the land of opportunity and cowboys.
Source: Have family all over.
Also, we pretty much see America as an enemy more often than not these days. You can shove that 51st state implication.
- Comment on What would have to happen to make everybody realize we weren't exaggerating when we said Trump would be like Hitler? 5 weeks ago:
As someone from outside, lol no.
Most Americans don’t understand that other countries have sovereignty as good as their own. Or that they are as good as any other people.
Okay, that bit is true. Hitler was a bit more than just oblivious, though.
- Comment on What would have to happen to make everybody realize we weren't exaggerating when we said Trump would be like Hitler? 5 weeks ago:
They don’t want Hitler, they just want everything he stood for with a few groups swapped out. If they actually wanted Hitler that would be bad, because dad/grandpa fought against Hitler.
Any apparent hypocrisy is just a technicality, and people only point it out because of their derangement syndrome. /s
- Comment on What would have to happen to make everybody realize we weren't exaggerating when we said Trump would be like Hitler? 5 weeks ago:
He would have to grow a tiny mustache and start speaking German.
Okay, maybe it’s not that bad, but it really does seem like people have trouble generalising the concept of a fascist outside of it’s historical visual trappings.
- Comment on Whats a good Resource on Learning 6502 Assembly, for someone who has little to no experience Programming? 1 month ago:
Wow, what a place to start!
- Comment on Stop trying to make ‘kagis’ a thing. 2 months ago:
We really need a single word, given how often it comes up.
- Comment on Low-quality papers based on public health data are flooding the scientific literature 2 months ago:
The motivation isn’t, but the technology to generate a slop paper is.
- Comment on The word literally makes me so irrationally angry 2 months ago:
Yes, I think it’s a pretty common pet peeve.
- Comment on Just blocked hexbear 3 months ago:
You’re right, it is absurd.
- Comment on Just blocked hexbear 3 months ago:
Your whole profile is “I’m a leftist theory guru”. And then you don’t actually have anything to offer when engaged.
- Comment on New ATHEIST community. 3 months ago:
And honestly, most of Lemmy is already pretty close, haha.
- Comment on Just blocked hexbear 3 months ago:
Not if you’re doing it purely for clout.
- Comment on Just blocked hexbear 3 months ago:
Humourism is a thing. Y’know, Hippocratese wrote about it. They used to do bloodletting to balance the humours.
- Comment on Just blocked hexbear 3 months ago:
Lol, who’s side are you on?
- Comment on Just blocked hexbear 3 months ago:
I’m pretty sure last time I read a thing you sent me and replied, you just told me to read more things.
- Comment on Just blocked hexbear 3 months ago:
Free thought, or aimlessly contrarian?
You could pretty much swap in flat Earth theory here and it would still make perfect sense.