Alt-BEAM Archive
Message #10114
To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@telus.net
Date: Fri, 11 Feb 2000 23:20:10 -0800
Subject: [alt-beam] Re: 74x240 question
Dennison Bertram wrote:
>
> ... Logic high for a xx240 is represented as + 5 volts.
The operating (i.e. supply) voltage range for the HC family is 2 to 6
volts. Logic high varies with the supply voltage.
Ben Hitchcock wrote:
>
> Ganging 3 drivers on the same chip.
I asked because a little know fact is that chip manufacturers do NOT
recommend running gates from different chips in parallel. Running gates
on the same chip in parallel is generally OK.
The reason is that you cannot guarantee that gates on different chips
will toggle at exactly the same input voltages, so you could get a
direct short between the parallel outputs.
BEAMers have been getting away with this, but mainly because of luck and
good manufacturing tolerances.
Since you're using the same chip, that obviously isn't the problem.
Regards,
Bruce
10115 Fri, 11 Feb 2000 23:06:39 -0800 Re: Light Duty Electric Welder Richard Piotter
> I've used larger welders before. My dad and I built a 52 foot wide, 8
> seat spot sprayer (for non farmers, it's a big thing with seats and
> spray guns to spray herbicide on weeds). I know about the UV and
> protection and stuff. I also know I can't use that big machine for small
> stuff. Right now I'm looking for something that can weld VERY thin
> material to things like motor shafts or frame work.
>
> I've seen joints where two metal objects are "melted through" at points
> to hold it together. This is what I am interested in doing primarily.
>
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