11 Mar
2005
11 Mar
'05
8:54 a.m.
if you are targeting 5.5us, then it is a 220pf cap. The formula for the pulse width for a
121 is 0.7 * R * C, where 220pf is 220 X 10-12 and R is 25000 then the time comes out to
5.5us. I think the "l" was just a mistype.
-----Original Message-----
From: Bill Sudbrink <wh.sudbrink at verizon.net>
Sent: Mar 11, 2005 7:14 AM
To: cctalk at classiccmp.org
Subject: Name that cap...
to jump out at me. Part of the accompanying text says: "The RC time
constant
is adjusted to give an output pulse width on pin#1 of the 74LS121 of 5.5
ls."
I assume "ls" is an oddball abbreviation for microsecond?