This is the power supply.
About two weeks ago, while fitting slide rails and stuff to the black rack, I dropped one of the cage nuts into the inside of the hollow metal framework struts. Thinks: "Bugger. Hmm... I know, I'll retrieve it with a small magnet on the end of something."
Well I have plenty of small magnets handy. I probably even have an actual extensible magnetic retriever somewhere. But finding it could take a while. And so I came up with the brilliant idea of holding a small magnet in the end of a thin surgical clamp - of which I have several and actually even know where they are.
Now one of the current 'to do' projects is some modifications to a big three-phase DC power supply. It's basically like an arc welder transformer, except originally intended to run a high intensity Xenon lamp. I'll be using it with the vacuum chamber rig.
Anyway, the unit was then sitting beside the door to the machine tool shed, with all its covers removed.
This is the power supply.
So, I'm walking past the transformer unit with the small cylindrical magnet held in the tip of a surgical clamp. At that instant the magnet slipped out of the springy, tensioned tip of the clamp. You know that sound? "Ping! Whizzz... tink! tinkle tinkle... silence."
Ahhh crap. I did NOT see where it went, but it sure sounded like the general direction was from the transformer unit. In which everything but the wiring is iron. In which the structure is very convoluted, with many nooks and crannies. Many of them closely adjacent to three phase 415V windings, that have only enamel insulation. Plus there's the central variable coupling core, which moves via a hefty worm screw - thus easily able to jam a small object into one of the windings.
Note to self: "Idiot! Now you absolutely have to find that magnet, before powering up anything in this part of the room. Especially the transformer."
This is the magnet. Which could have been anywhere.
Spent an hour going over the inside of that transformer with a torch and mirror. Did not find it. Looked everywhere I could think of in nearby places. Still no sign of it. Decided to leave it a while, maybe it would turn up when I wasn't looking for it. (Yes, this sometimes works!) But this time, nothing.
Time goes by, with that project completely stalled due to 'lost spanner in works' fear. Today, when I happened to pull the plastic dust cover off to move the unit to get at something else, AH HA! There it is!
Can you see it?
What a feeling of relief!
Of course it was in the worst possible place, in terms of finding it. Not in the actual transformer, where I exhaustively examined every inch of surface. Not anywhere on the machine cabinet, inside or out, where it would have been easily seen. Nope, it found a spot where it blended in really well, and also wouldn't be felt when using the handles to move the machine.
Clever little magnet! Obviously evolved in a hostile environment, where magnet carnivores with sharp eyes eliminated all its less cunning ancestors.