15 Apr
1999
15 Apr
'99
7:27 a.m.
At 10:45 PM 4/14/99 -0400, Allison wrote:
<From CLASSICCMP-owner(a)u.washington.edu Wed Apr 14
21:46:30 1999
I have one in a clear pen barrel with a point and and
a cliplead, very
handy! It's pretty easy to tell, high low and something that's pulsing
even at high rates. Another handy item is a 4040 cmos counter to make
fast things into tones (earphone). That trick came from the NS* disck
controller troubleshooting hints.
Hey! I thought of a 4040 tester a few years ago on my own. I guess it isn't
original after all. It is small and useful, It has shown for example, a Z80
quartz clock oscillator which started oscillating on its 3'rd overtone (the
Z80 would not run). Another case was a 54LS74 as a toggle FF which failed
and the Q output followed the clock input instead of divide by 2.
-Dave