Modern Electronics (was Re: List charter mods & headcount... ; -))

From: Paul Koning <pkoning_at_equallogic.com>
Date: Mon Jun 21 13:37:11 2004

>>>>> "der" == der Mouse <mouse_at_rodents.montreal.qc.ca> writes:

>> There was an idea some time back that if we ever get to the moon
>> that we could be using "open-air" valves (tubes) in the vacuum
>> there for high powered devices

 der> Is the "open-air" vacuum on the Moon a hard enough vacuum for
 der> vacuum-tube technology? Does it depend on whether it's day or
 der> night (and therefore whether there is solar wind pouring in)? I
 der> know that _some_ vacuum-tube technology - notably CRTs - depends
 der> on electrons having a mean free path well over the tube size,
 der> and that needs a pretty hard vacuum.

That's true for all vacuum tubes. If that condition isn't met, you
have a "gas filled tube" -- something you occasionally want, but not
very often.

I think even solar wind is a pretty hard vacuum.

>> - with the benefit that goes with the better radiation resistance
>> that goes with valve technology.

 der> Is it valves that give you rad-hardening, or size? A transistor
 der> the size of a valve would, I suspect, be inherently pretty
 der> rad-hardened. (Certainly the largest transistors I've seen are
 der> far smaller than the smallest valve I've seen. Probably by
 der> about an order of magnitude, once you strip each one down to the
 der> operating portion.)

Take a look at power transistors sometime. Some come in "hockey puck"
packages, which describes not just the shape but also the size. And I
think a fair fraction of that package is die...

      paul
Received on Mon Jun 21 2004 - 13:37:11 BST