Alt-BEAM Archive
Message #00210
To: "Paul B. Webster VK2BZC" pwebster@clinipath.com.au
From: Bob Shannon bshannon@tiac.net
Date: Fri, 05 Feb 1999 19:45:04 -0800
Subject: [alt-beam] Re: Schmitt trigger
Paul B. Webster VK2BZC wrote:
>
> RoboDR@aol.com wrote:
>
> > Is it possible to get a single Schmitt trigger inverter like the ones
> > used in the microcore? Or is the lowest number u can get 6?
>
> And this has spawned an *amaazing* discussion in some strange fashion!
>
> Look, the simple answer is "Why on *earth* would you want to?".
>
> It's like (though you might not know this ;-) Sabin polio vaccine only
> coming in 10-dose vials, so if you use only one dose in a day, it only
> keeps for 24 hours and you have to throw out the rest. So you say "Why
> not make it in single or 2-dose vials?". Answer is - they could, but
> since the vaccine itself is dirt cheap (by comparison at least), it'd
> cost exactly the same, or *more* because they'd now have two in the
> inventory. The cost is all in the packaging.
>
> It simply is *not worth* building them in less than a six-pack. Using
> (H)CMOS logic, unused gates consume *zero* power (as long as you ground
> the inputs), so you just forget them. A SMD package is so small you
> wouldn't want to use a smaller one (but could probably obtain it as a
> raw chip if you needed to). Therefore the question has no real meaning.
Ha!, you have never needed one extra gate, and had no room for it before
eh?
It happens all the time, thats why those chips exist. I see prototypes
with
single gate 'fixes' quite often at work.
Also, their smaller form factors allow construction methods you cannot
imagin
using with hex SMT parts, like having an NV right at each sensor or
motor driver rather than having all the wires converge on a single
'brain'.
------------------------------------------------------------------------
eGroup home: http://www.eGroups.com/list/alt-beam
Free Web-based e-mail groups by eGroups.com
Home