Very cool. Couldn’t get the pictures to load in any higher res. Would love to see more of the detail
A modern 8 bit design, built using 1950s thermionic valves
31–40 of 87 posts
Re: A modern 8 bit design, built using 1950s thermionic valves
#32> 200 amps Something I’ve been curious about: is the current actually required for the thermionic effect, or just the heat? Could you lower the current requirement by thermally insulating the tubes?
There are tubes made which share one heater. For an exotic example with a working web page, see this tube where two triodes and one pentode share the same one heater filament.
https://vinylsavor.blogspot.com/2021/11/tube-of-month-6bh11....
This one has two diodes and two triodes.
https://vinylsavor.blogspot.com/search/label/6AY11
And in this very design, they chose "6N3P valve contains 2 triodes around a single heater, halving the physical size and power requirements."
There may have been tubes made where the triode function can be pretty rough (sufficient for a digital circuit) and several of them could share one enclosure. In the tubes shown above, apparently the limit was the number of pins on the socket - but also that all these active elements do not share any pin.
Insulating the whole thing would run into issues like burning wire insulation.
Re: A modern 8 bit design, built using 1950s thermionic valves
#33Re: A modern 8 bit design, built using 1950s thermionic valves
#34"But most important of all, is to have a lovely wife, who knows you're daft as a brush, and that life together is brilliant." Hold out for the partner that cheers you on when you're doing what you love.
> Hold out for the partner that cheers you on when you're doing what you love. If only it were that easy. Those kinds of people are few and far between. I’m almost 50 and I don’t think I’ve ever even met a woman who has actively encouraged me about a single thing. I’ve been married twice and have 4 daughters.
Hence the hold out. I (50m) didn’t meet her until I was 30: until that time I dated and had few months relationships with a lot but it never felt quite right. Which became blatantly obvious when I met my wife.
Re: A modern 8 bit design, built using 1950s thermionic valves
#35> When all the valves are glowing, I check the fire extinguisher is full, and run the code. It wasn't until working with valve hardware that I finally grokked the original difference between a cold boot and a warm one.
♫ "And when they turn the power on, it's sure to dim the lamps / At plus and minus 16 volts and fourteen hundred amps." -- Frank Hayes
Re: A modern 8 bit design, built using 1950s thermionic valves
#36> When all the valves are glowing, I check the fire extinguisher is full, and run the code. It wasn't until working with valve hardware that I finally grokked the original difference between a cold boot and a warm one.
♫ "And when they turn the power on, it's sure to dim the lamps / At plus and minus 16 volts and fourteen hundred amps." -- Frank Hayes
Song audio: https://m.youtube.com/watch?v=bMS6G83NqFQ
Re: A modern 8 bit design, built using 1950s thermionic valves
#37> When all the valves are glowing, I check the fire extinguisher is full, and run the code. It wasn't until working with valve hardware that I finally grokked the original difference between a cold boot and a warm one.
♫ "And when they turn the power on, it's sure to dim the lamps / At plus and minus 16 volts and fourteen hundred amps." -- Frank Hayes
Telephone central exchanges used to have enormous lead acid battery (like automobile batteries, the starter motor not the EV kind) arrays if they lost power.
It was amazing to see the battery array discharge ammeter at 5000 amps when utility power went out.
Re: A modern 8 bit design, built using 1950s thermionic valves
#38Very cool. Couldn’t get the pictures to load in any higher res. Would love to see more of the detail
Very hot.
Re: A modern 8 bit design, built using 1950s thermionic valves
#39> 200 amps Something I’ve been curious about: is the current actually required for the thermionic effect, or just the heat? Could you lower the current requirement by thermally insulating the tubes?
They are insulated really well - by vacuum! I'm actually surprised by the figure, though. A small tube requires about 300 mA at 6 V, and the trick is that you can connect the heaters in series instead of doing it all in parallel and pumping out a ton of amps at a very low voltage. They could've done 10 tubes in series at a reasonably safe 60 VDC, and they'd only need 20 amps. Back in that era, because both valves and…
and the trick is that you can connect the heaters in series instead of doing it all in parallel and pumping out a ton of amps at a very low voltage.
Yes, this is what a lot of tube equipment did, as they are naturally high-voltage, low-current devices; here is one notable example:
Re: A modern 8 bit design, built using 1950s thermionic valves
#40That’s some serious power draw. Truly impressive work!