Hello again, and my apologies for the long time since the last one. Today I’ve got a quick topic to discuss, and although it’s fairly obvious, I don’t think it’s documented elsewhere online.
I’m working on a project for which I’ll be building a fairly sizable core memory array (see here for the first post on this topic, which covers the construction of a small demonstration array). As noted in the original post, it is simple to address a huge number of cores in an array because the core material will only change magnetic state when a sufficiently large current is passed through it; any smaller current will leave the core in its initial state. Thus, by passing only half the necessary state cha
But how much current is necessary? There is no standard (to my knowledge) that says all memory cores require x milliamps to flip. If you buy a set of random cores on eBay like I did, this is a question that needs to be answered before any further design work can take place. So I tried a few methods, found some things that worked and some things that didn’t work so well, and decided to share my results.