22 Dec
2025
22 Dec
'25
7:42 p.m.
On Dec 21, 2025, at 8:16 PM, Brian L. Stuart via
cctalk <cctalk(a)classiccmp.org> wrote:
So Santa had his sleigh out for some test drives tonight. For
ballast (the real gifts won't be loaded until Wed night), he used
a big stack of engineering drawings from the 1940s. Fortunately
for us, his "spirited" driving included one turn that was too
tight and out flew the drawings, where they landed on my lap. For
anyone who's as eager as I am to geek out over 1940s computer
design, I share them with you here:
http://cs.drexel.edu/~bls96/eniac/drawings/
Wow.
I glanced at a few of them. Was surprised to see an inverter using a 6L6. Then looked a
little further and came across an element that uses an 807.
The 6L6 and even more the 807 are rather substantial power tubes. 807s are commonly seen
in amateur radio transmitters in the 1940s and 1950s, good for 50 watts or so power
output. I have a couple, they are very nice tubes. I don't remember the 6L6 ratings;
20 watts, perhaps? Both are also rather large, the 807 especially, when compared to
typical "receiver" tubes.
paul