Hi
Sorry for neglecting to check the thread.
I will answer as best I can. Consider that I researched hard, but before this, in hindsight,
didn’t know much about transformers, and didn’t understand at all the concept of pulse transformers.
The cores I got quoted on eBay as 1mm cores, it turns out to be the outside diameter, but there isn’t much meat to them.
You can definitely test hysteresis quality of a single core probably better than me, but I knew the particular ferrite due
to the other two previous core RAM experiments. I got mine from the same eBay seller.
Two people have done a successful experiment that I know, one a 32 bit RAM, and the other, a 1 bit RAM so far,
but Wayne’s page does go into some more practical detail about testing one bit.
You simply switch it’s state with a single current wire while looking at another scope channel at a sense wire.
If you can alternate current direction along the current carrying wire, you can observe a pulse from the sense wire
on the other channel if the state changed. Wayne has documented that well.
There would be better ways to test the rectangle loop pattern, but if you can see a switch pulse then the core has some hysteresis quality.
With regard to storing a third state....
Maybe if you could operate it faster than it could switch you might be able to demagnetise it, and sense a weaker pulse for the initial magnetisation.
My understanding of the core and the hysteresis loop is they are truly bistable and would not store a partial state.
Like a rubber band being pulled on until it breaks suddenly.
If the core did not snap it’s direction very fast like a spring you would not receive the sense pulse,
and there is a threshold where that occurs.
I can hardly wind up to 12 or so turns around a 1mm core.
Which is inside diameter of those cores? Why not to use slightly bigger one since it is still 8 x 8 array I guess?
I'll have in hands a lot of those FRH035050 Ferrocore ferrite beads which is 5mm long, outside diameter 3.5mm and internal 0.65mm.
At least they specify core material as Ni-Zn, but probably its histeresis is bad for core memory.
It looks like oryginal internal thick wire can be easy removed and custom thin windings inserted instead.
However, I'd like to take advantage of toroid length to multiply its inductance while keeping outside diameter below 5mm, but this is specyfic to other low power tiny SMPS project, but I thought that maybe those ferrite bead Ni-Zn could be also usable in core memory experiment, but I've no datasheet how its histeresis might look like
Anyway, maybe did you experimened with demagnetization of those core memory toroids?
I mean, maybe it is possible to store not only 0/1 bit for given saturated core flux direction, but... 3th state with very small residual magnetizm after demagnetization of core vere performed?
Is it possible to findout somehow that core memory was never set before to 0 or 1, so in theory we could have three core states with different residual magnetism (Brm):
+Brm
0Brm
-Brm
Basicly, I'd like to know not only if core is in +/-B residual magnetism state after magnetization (0 or 1 bit set), but if it was ever magnetized (set to bnary 1 or 0) and not sure if is it possible read somehow this 3rd core memory state to detect this?
Do you use this single-diode transfer loop concept shown in video I've linked above to read/write core memory or different method?
Trying to figureout howto check if core was magnetized, than when our read were it wasn't even if we used destructive method, we could perform demagnetization to "store" again this core state