multi electrode gas discharge tube (emp bus protection) - Page 1
Forum section: electronics / projects

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 04, 2016, 03:15:08 am
content: Are there GDT's available that have more then 3 electrodes? i.e. gnd + <2 signalsWhy? common mode current + multiple GDT's = differential mode currentLike say I wanna protect a entire bus from a nasty EMP. Do they have chips that have entire GDT arrays on them?If not, it seems reasonable to make one using vacuum tube manufacturing techniques .. could be interesting DIY experiment

author: SeanB
author_rank: Super Contributor
timestamp: January 04, 2016, 06:10:06 am
content: No, they come in single or dual only. For a bus you simply put a series along the bus, each doing 2 lines. In any case a GDT is not going to protect a bus, as they are both way too slow on turn on, and the voltage required is so high in any case that the bus buffers will fry long before they turn on. you probably are better off with Transorb arrays, which do come in bus clamping versions with multiple diode clamps to a common transient suppression unit in a single plastic package.

author: Gyro
author_rank: Super Contributor
timestamp: January 04, 2016, 09:22:01 am
content: I hope you're not refering to EMP in its formal sense!If so, you need some very specific GDTs and some very nasty testing due to the very steep rise time involved.

author: SeanB
author_rank: Super Contributor
timestamp: January 04, 2016, 09:27:12 am
content: He is not in Tehran or Tel Aviv, so that one is unlikely. Probably referring to induced current from close lightning strikes. Why you want a long bus is beyond me anyway, it will be very slow.

author: Towger
author_rank: Super Contributor
timestamp: January 04, 2016, 06:54:22 pm
content: You can get chips designed to detect an EMP from a blast. They typically are used in satellites to allow them to shut down and reboot in the event some nutters get carried away.If you search the forums, there is a discussion on them.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 05, 2016, 05:29:38 am
content: interesting. I think a transorb array would benefit from the additional protection of GDT.and yes, i am interested in a nuclear generated EMP. why? because i found it interesting. a proper nuclear generated EMP blast would require layers of protection, all critical to circuit survival.i don't plan on testing anything (how could i test it without a time machine to starfish prime?), but it just seems that it would be trivial for a company skilled in the art to make say, an octal gas discharge tube.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 05, 2016, 05:56:35 am
content: Well, you can certainly buy them...Nixie tubes aren't rated for surge currents though.Tim

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 06, 2016, 01:09:59 am
content: has there ever been declassified circuits used in nuclear weapons guidance systems ?particularly interested in protection from things like neutron flux/etc. not the actual weapon part of it

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 06, 2016, 04:18:04 am
content: Wouldn't think it's a big deal until the couple microseconds before everything goes splat. A lump of plutonium isn't really all that hot, until it goes off. (Give or take, I don't know how much effect the intiator has, just sitting there.)Tim