Hi, all,
From the amount of traffic my questions spawned, I
thought it only fair
to post a follow-up. I built the 74LS02 circuit nearly as
described,
but with no cap between the PET and the horizontal sync inverter. I
wasn't surprised when I got nothing on an LCD with composite input, so
I dragged out the 9" mono security monitor and was instantly rewarded
with a PET BASIC prompt - the only problem was that I couldn't lock
in the horizontal. I could get close, so that it was mostly stable,
but over time, it would roll faster and faster, no matter how I
tweaked the monitor.
I tried the "PET Revealed" trick of a pot on the hsync pull-down, but
that didn't seem to make much of an impact, and neither did removing
it entirely.
So I was able to see the PET work, but from a use standpoint, don't
quite have the right tweaks on the basic circuit. I'm out of time
for the season, or I'd keep fiddling with it (we could get new folks
in here in as little as a week, if all the early-season plans go
well, and weather permitting, as always).
Thanks for all the feedback. I understand things a lot better now,
and I'm happy to say that the first time I powered it up, I got
recognizable video, even if it did list to port a bit.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 16-Oct-2008 at 15:00 Z
South Pole Station
PSC 468 Box 400 Temp -59.3 F (-50.7 C) Windchill -86.4 F (-65.8 C)
APO AP 96598 Wind 7.0 kts Grid 336 Barometer 672.2 mb (10924 ft)
Ethan.Dicks at
usap.gov http://penguincentral.com/penguincentral.html