That's an excellent heads up, Glitch.

Note: those Honeywell hall effect switches are in demand by certain people on deskthority, who I've been lead to believe use them for purposes very much against the spirit of vintage computing. (newly made retro-style USB homebrew keyboards using the keyswitches ripped out of an old symbolics or similar hall-effect keyboard, for instance)

Be wary of whoever you sell them to! It'd be a shame if these are wasted on a modern project, rather than for repairing something vintage which can't use anything except the original parts. Its practically impossible to retrofit mechanical switches in place of these, for instance.

I know of someone who is looking for some of these same exact switches to fix a broken symbolics keyboard for use on an actual symbolics machine.
Contact me if you have some of them available, and I'll pass it along.

On 12/7/2016 8:55 PM, Herb Johnson via vcf-midatlantic wrote:

A colleague of mine, is trying to repair his mid-1970's keyboard. He may well find old-stock unused keyswitches, but I'm betting not. They were likely made by MicroSwitch, owned at some point by Honeywell. They are Hall-effect. They have four pins, they need 5V power. This is not a common microcomputer.

Here's a link to deskthority.net, of what the keyswitches look like.

https://deskthority.net/wiki/Micro_Switch_SD_Series

specifically:

https://deskthority.net/wiki/File:2011-11-07_16.15.40.jpg

But there's lots of variations. No point in describing them further, most won't have these keyswitches. If you have something like this, and can unsolder several (and one for inspection), contact me directly and we'll go from there.

Herb Johnson