24th Nov 2020, 6:08 pm | #61 |
Octode
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Re: Would we have got to the moon with no semiconductors?
"Yes, in the vaccuum of space, but not in a spacecraft that contains air.
Also, exposed valves without a glass envelope would I suspect interfere with each other. How do you stop electrons emmited from the heater of one valve from landing on the anode of a different valve, or indeed on any other exposed conductive part that is positive with respect to the valve heater". Would this be solved by screening? Perhaps minute valves could be printed with some sort of enclosure, and the whole unit evacuated. It wouldn't need to be a heavy case if it was open to space. Maybe making more sense if manufactured in space! |
24th Nov 2020, 6:38 pm | #62 | |
Nonode
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Re: Would we have got to the moon with no semiconductors?
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24th Nov 2020, 6:49 pm | #63 |
Dekatron
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Re: Would we have got to the moon with no semiconductors?
So am I! Thanks for starting it, I'm following with great interest.
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Al |
24th Nov 2020, 8:40 pm | #64 |
Dekatron
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Re: Would we have got to the moon with no semiconductors?
Look at it the other way round. How do you get something of that weight into orbit, let alone to the moon and back. Scaling up launch vehicles must be as big a challenge.
Theoretically possible using valves, but as impractical as was the valve CD player mooted recently. |
24th Nov 2020, 9:21 pm | #65 |
Heptode
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Re: Would we have got to the moon with no semiconductors?
Maybe in parts, assembling them in an orbit around earth? There were scenario's like that developed already in the 60's for the period after the Apollo program (target: Mars).
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24th Nov 2020, 9:57 pm | #66 | |
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Re: Would we have got to the moon with no semiconductors?
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24th Nov 2020, 9:59 pm | #67 |
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Re: Would we have got to the moon with no semiconductors?
OLED is a much more primitive and advanced (at the same time) technology, though. It would have existed (as a development of EL technology) regardless of LED technology existing.
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24th Nov 2020, 10:07 pm | #68 |
Octode
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Re: Would we have got to the moon with no semiconductors?
Don't forget magnetic amplifiers and saturable cores
All capable of amplification and switching I believe these were used in early missiles Following with great interest Trev |
25th Nov 2020, 2:12 am | #69 |
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Re: Would we have got to the moon with no semiconductors?
I seem to remember reading, at some point in the distant past, that fluidic logic was the future.
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25th Nov 2020, 6:06 am | #70 | |
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Re: Would we have got to the moon with no semiconductors?
Quote:
Doing it with electrons in vacuum rather than electrons in crystalline solids has a number of differences. The voltage drop across switches will have to be a lot larger. Creating focused electron beams that don't stray into neighbouring elements is going to set a larger physical size. So there are going to be unavoidable ratios of parameters which will set limits on speed, density and overheating. Of course, there could be some new discovery or invention which circumvents these limitations, but maybe it would be sufficiently different to known thermionic techniques that such a name would no longer fit anyway. It's something unexpected even now. It's an interesting discussion. I wonder more about guided light, erbium doped light guides with gain and distributed optical pumping to power it all. We seem to be getting towards limitations of our current style of doing things, but that impression has been floating around for decades. We've had all sorts of things which looked futuristic.... Magnetic bubbles, wafer scale integration, 'transputer' style architecture. 3-D construction. All sorts of things and some of them aren't actually as dead as is often thought. The future has unpredictable elements and even outright surprises in store for us. David
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25th Nov 2020, 8:16 am | #71 | |
Nonode
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Re: Would we have got to the moon with no semiconductors?
Quote:
It even shows how to make a bistable device using something call "wall attachment" and shows a picture of a commercial device made by Corning "All the wall attacment devices so far shown can operate at pressures between about 1 and 20 psi, but the nominal working pressure is around 2 to 3 psi. The signal pressure varies with the supply but is generally between 5 and 15% of supply pressure. Switching speeds can be as fast as 1,000/sec"! Although being a purely mechanical device its probably OT for this forum....... Peter |
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25th Nov 2020, 9:30 am | #72 | ||
Octode
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Re: Would we have got to the moon with no semiconductors?
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25th Nov 2020, 10:02 am | #73 | ||
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Re: Would we have got to the moon with no semiconductors?
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25th Nov 2020, 10:05 am | #74 |
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Re: Would we have got to the moon with no semiconductors?
Extra weight into orbit?? There you all go again....
We think of valves as big and clunky things because what you have been (OK, still are) looking at was old technology. Domestic equipment was having to make do on 1930's technology because the state-of-art stuff went to the military in WW2, and there was a bit of a slow-down after the war because no-one had any money. If there were no semiconductors on the horizon, the military would have been (in fact were) driving forwards. There was already kit using tiny little valves so that very poratble gear could have complex circuits. The next wave was coming, but it never made it beyond niche uses because of the change to semiconductors. A classic "bad press" for valves was the time taken to warm up. That was nothing to do with valve heaters of course! It was the deliberate slow-start of large series heater chain TVs and then a second wait for the EHT heatup. In WW2 there were transceivers that turned the transmit filaments on when you pressed the PTT - the delay was only about a second. On size, take an early almost-computer like Colossus. It actually isn't that big, but it was made from 30's valves mounted in GPO racks because it was all they had spare. Move forwards two generations and I am sure it would go in a small suitcase. So what would it be like in another two generations of development? One of the great misconceptions about early computers was how "big" they were. I worked on these systems and what surprised me was why they were big. It wasn't because there was a lot of circuitry. The rows of cabinets were not so full, and a lot of it was pumps, power converters, disc and tape drives units and cabling. The actual "computer" in the sense of processor and memory was really quite small. The mini revolution was not so much about shrinking the components as realizing that if you did away with the peripherals and rack-mounting and connectors - the result was a single board! |
25th Nov 2020, 12:59 pm | #75 |
Pentode
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Re: Would we have got to the moon with no semiconductors?
Perhaps with progress in digital computers, the capabilities of analogue computers tend to be forgotten.
This link is mostly in German but includes some English, maths, circuits and photographs of Helmut Hoelzer’s Fully Electronic Analog Computer: https://www.cdvandt.org/Hoelzer%20V4.pdf Synopsis: ‘A fully electronic general-purpose analog computer was designed by Helmut Hoelzer, a German electrical engineer and remote-controlled guidance specialist. He and an assistant built the device in 1941 in Peenemunde, Germany, where they were working as part of Werner von Braun’s long-range rocket development team. The computer was based on an electronic integrator and differentiator conceived by Hoelzer in 1935 and first applied to the guidance system of the A-4 rocket (Goebbels, the Nazi propaganda minister dubbed, V 2, AOB). This computer is significant in the history not only of analog computation but also of the formulation of simulation techniques. It contributed to a system for rocket development that resulted in vehicles capable of reaching the moon.’David |
25th Nov 2020, 1:01 pm | #76 | |
Heptode
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Re: Would we have got to the moon with no semiconductors?
Quote:
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25th Nov 2020, 2:29 pm | #77 | |
Nonode
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Re: Would we have got to the moon with no semiconductors?
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Would act as a sort of ROM. Peter |
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25th Nov 2020, 2:49 pm | #78 | |
Heptode
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Re: Would we have got to the moon with no semiconductors?
Quote:
The excellent .pdf posted earlier, although mostly in German, has at the very end a diagram and English description of how the V2 guidance system worked, all analogue valves !. Cheers, Buzby |
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25th Nov 2020, 3:48 pm | #79 |
Dekatron
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Re: Would we have got to the moon with no semiconductors?
There was a proposal about 30 years ago to make tiny triodes actually by etching a silicon substrate but they didn't use any semiconductor properties AFAIK. The reason eas to make radiation-hard devices.
The cathode was a sharp tip using field emission rather than thermionic emission. The final device would be smaller than the mean free path of an electron in air at atmospheric pressure meaning it didn't have to go in an evacuated envelope even on earth. I have no idea if anything came of this, but if the transistor hadn't been invented then it's possible integrated circuits woul use such devices. |
25th Nov 2020, 3:50 pm | #80 | |
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Re: Would we have got to the moon with no semiconductors?
Quote:
I learned to grapple with mainframes on those. But I was recently surprised to learn that I had also encountered the same machine in a tiny box on a Nimrod aircraft! There was a military version of the same great big computer that fitted in a small box, dedicated to processing radar. Again showing that the reason for the big machines in many caninets was maintainance convenience and ease of replacing modules. If you really wanted small and light - you could have it! |
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