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Where can i get small toroids for magnetic core memory? Answered

I have really wanted to do this but I could never find those pesky rings!

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I think i am going to get: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330433810462&rvr_id=&crlp=1_263602_263622&UA=WVS%3F&GUID=bb6efd981260a0aad2c2bf02fff80f71&itemid=330433810462&ff4=263602_263622#ht_500wt_1154 This will work right? It will change states when current running through wire magnetizes it.

What I am worried about though is if the will change the polarity of their magnetic field in the way necessary for magnetic core memory. I don't know if cores were purpose built with specific material properties but I am hoping they weren't and that all small ferrite toroids will work.

I'll ask my father, who is an expert on ferrite properties. Steve

Right, I asked. "Only HARD ferrites are used for core memory - they have a virtually square BH curve. Hard ferrites exhibit permanent magnetism, soft ones don't." Steve

If I were you, I'd look at buying some old core memory and re-energising it, rather than sewing my own. Steve

I can't find old core memory either. What do you mean by re-energizing it? Do the toroids become demagnetized or something?

http://cgi.ebay.co.uk/USSR-Soviet-military-ferrite-core-memory-HUGE-CORES-/220616557908?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item335dc58554

Yes, but its got cores on it. The one the same guys had sold that was intact went for over 150 USD ! That means the 4 boards I have from a computer that was broken up at University must be worth a fortune by now. Steve

Yes, I forgot the original quest was for the cores.

Gosh. Those are sure tiny little things. I'll bet the people sewing those things went bonkers after a while.

According to some of the sources about the Apollo guidance computer, the core rope memory of the AGC was know as LOL memory, for Little OId Lady memory - it was hand stitched by, well, little ol d ladies who could follow a knitting pattern !

Ya, I heard that on a discovery channel show about the apollo missions from someone being interviewed who actually worked on the mission.

Fascinating. From the picture, I calculate that they're exactly 1/33 inch in diameter (1/13 cm). That seems a slightly non-obvious form factor to choose.

I mean make the old electronics work, the core should work forever. Steve

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Burf

8 years ago

All of the new fluorescent bulbs I've opened up have one in the circuit board. I once saw an Instructable for opening the things up. I presume it is still available through the Search function above.

Cor that sounds like a lot of work!

Do you mean core that sounds like a lot of work ? ! Steve

Yes but I was being coreful not to make the pun tooooooo obvious.