u/Comfortable_Bus_7863

I've been trying to make sense of the relay-based timing sequence system used to time and coordinate the various experiments around the 1945 Trinity nuclear test. Can anyone tell me about Allen-Bradley Bulletin 20 contactors and "BJX" relays? I'm almost certain the author (one of the scientists involved in setting up the timing system) goofed and meant to type "Bulletin 200." He mentions Union Switch & Signal KP biased-polar relays, for which I've found enough information. But information on "BJX" relays eludes me. Any help?

https://nsarchive2.gwu.edu/nukevault/ebb475/docs/doc%203%20sandia%201959.pdf "A Survey of Nuclear Weapon Safety Problems", Sandia 1959. Some interesting points:

"It has been suggested that [a] 'go' signal include an otherwise unknown code or combination necessary to unlock an appropriately designed bomb arming system." Seems that they were beginning to think in the direction of PAL.

Regarding sealed-pit weapons: "Through a connector on the warhead package are introduced the gas-boost arm signal, two distinct and independent X-unit arm signals, and the fire signal."

For weapons using thermal batteries: "Two distinct electrical arming signals are required: one to close the high voltage switch between the battery and X-unit, the second to cause battery activation."

Weapons using chopper/converter power supplies also require two arming signals, to wit: "One to start and run the chopper motor, a second to supply the low voltage power to the transformer . . . both these arming functions require continuous power."

But the thing that really caught my attention was this idea under the heading of "Locked Warhead Container":

"To force special handling, the key might well be loaded with Cobalt 60." Sounds like a fun time!

ETA: the whole idea of choppers, dynamotors, etc. in nuclear weapons amuses me to an inordinate degree. Like something from the Acme catalogue in Looney Tunes. "The warhead was just sitting there and it started making this noise! Let's get outta here!"