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Jeri Ellsworth managed to make transistors in a pottery kiln, starting with modern wafers. She said it took three years of research and interviewing graybeards

Jeri Ellsworth managed to make transistors in a pottery kiln, starting with modern wafers. She said it took three years of research and interviewing graybeards who were working on it in the 1970s. Makes me hope she wrote that stuff down.

mechanical_fish 15y ago
That sounds about right. But "build a transistor, given a wafer of pure undoped silicon" really is isomorphic to that joke about using a million dollars to make a million dollars.
0x12 15y ago
The wafer is the hard part. That's why I suggested making glass first, it's a good primer on the kind of gear that might one day lead up to the tooling you'll need to make silicon pure enough to make a transistor. You'd be much better off choosing a road that leads via relays, that's just metalworking and some coating. Vacuum tubes would still be an order of magnitude easier than silicon. Think sandy beach + pit mine, before you turn that into a working transistor you're going to be busy for a while.
- JoshTriplett 15y ago
  > You'd be much better off choosing a road that leads via relays One Portland State University professor built a relay computer, with an ALU: http://web.cecs.pdx.edu/~harry/Relay/ http://web.cecs.pdx.edu/~harry/Relay/ Quite impressive to see it in action.
  - 0x12 15y ago
    Thank you for that link. I took the liberty of re-posting it separately, it is one of the coolest things I've ever seen built. Besides the memory (and that would just add another couple of 10's of thousands of relays for a usable machine) that looks like the shortest direct path between 'man on a beach' and having a working automatic computer with a practical degree of reliability.
    - JoshTriplett 15y ago
      "practical degree of reliability" seems somewhat debatable; it apparently burns out components fairly often when running. IIRC it uses quite a bit more juice than it needs to, which might have something to do with it, so perhaps it could be made more reliable.
      - 0x12 15y ago
        Relay contacts tend to spark when they engage each other. You can get rid of most of that sparking by adding diodes but that would be cheating (semiconductors again), to a lesser extent using small neon bulbs across the coils (that will still take them up to 90V though). With 'practical' I meant that you would be able to run programs to completion for for instance numerical problems. Vacuum tube computers suffer from different problems (such as tube filaments burning out) and I really wonder whether a well designed vacuum tube computer would be more or less reliable than a well designed relay based computer. Vacuum tubes got awfully small in their final days but the voltages involved and the heat make me believe that relays would probably be more reliable, but likely also more expensive and much slower.
        stan_rogers 15y ago
        A capacitor will deal with the sparking -- they've been used (under the name condenser) in conjunction with points and mechanical distributors in internal combustion engines for years. This all presupposes a memory of methods to create reliable electricity, though -- including rectification and filtering, if that memory involves alternators. A purely mechanical representation of computing would probably be more practical in a forced Iron Age reboot of society. A treadmill-powered version of Photoshop would be a bitch, of course, but number crunching (at the level needed for serious societal progress) would come fairly quickly.
        JoshTriplett 15y ago
        The relay computer does use a capacitor: a huge 1F capacitor.
- mechanical_fish 15y ago
  Relays! I'm ashamed I didn't suggest those first. One of life's most precious moments was touring the MIT Tech Model Railroad Club during the last year of their old switching system's operation. It was built around some old relay-based telephone switch the size of a couple of refrigerators, and the whole thing made these awesome clacking noises. It also emitted this constant, periodic metallic click, like a metronome, which I was told was the clock.

mechanical_fish 15y ago

That sounds about right. But "build a transistor, given a wafer of pure undoped silicon" really is isomorphic to that joke about using a million dollars to make a million dollars.

0x12 15y ago

The wafer is the hard part. That's why I suggested making glass first, it's a good primer on the kind of gear that might one day lead up to the tooling you'll need to make silicon pure enough to make a transistor. You'd be much better off choosing a road that leads via relays, that's just metalworking and some coating. Vacuum tubes would still be an order of magnitude easier than silicon. Think sandy beach + pit mine, before you turn that into a working transistor you're going to be busy for a while.

JoshTriplett 15y ago
> You'd be much better off choosing a road that leads via relays One Portland State University professor built a relay computer, with an ALU: http://web.cecs.pdx.edu/~harry/Relay/ http://web.cecs.pdx.edu/~harry/Relay/ Quite impressive to see it in action.
- 0x12 15y ago
  Thank you for that link. I took the liberty of re-posting it separately, it is one of the coolest things I've ever seen built. Besides the memory (and that would just add another couple of 10's of thousands of relays for a usable machine) that looks like the shortest direct path between 'man on a beach' and having a working automatic computer with a practical degree of reliability.
  - JoshTriplett 15y ago
    "practical degree of reliability" seems somewhat debatable; it apparently burns out components fairly often when running. IIRC it uses quite a bit more juice than it needs to, which might have something to do with it, so perhaps it could be made more reliable.
    - 0x12 15y ago
      Relay contacts tend to spark when they engage each other. You can get rid of most of that sparking by adding diodes but that would be cheating (semiconductors again), to a lesser extent using small neon bulbs across the coils (that will still take them up to 90V though). With 'practical' I meant that you would be able to run programs to completion for for instance numerical problems. Vacuum tube computers suffer from different problems (such as tube filaments burning out) and I really wonder whether a well designed vacuum tube computer would be more or less reliable than a well designed relay based computer. Vacuum tubes got awfully small in their final days but the voltages involved and the heat make me believe that relays would probably be more reliable, but likely also more expensive and much slower.
      - stan_rogers 15y ago
        A capacitor will deal with the sparking -- they've been used (under the name condenser) in conjunction with points and mechanical distributors in internal combustion engines for years. This all presupposes a memory of methods to create reliable electricity, though -- including rectification and filtering, if that memory involves alternators. A purely mechanical representation of computing would probably be more practical in a forced Iron Age reboot of society. A treadmill-powered version of Photoshop would be a bitch, of course, but number crunching (at the level needed for serious societal progress) would come fairly quickly.
        JoshTriplett 15y ago
        The relay computer does use a capacitor: a huge 1F capacitor.
mechanical_fish 15y ago
Relays! I'm ashamed I didn't suggest those first. One of life's most precious moments was touring the MIT Tech Model Railroad Club during the last year of their old switching system's operation. It was built around some old relay-based telephone switch the size of a couple of refrigerators, and the whole thing made these awesome clacking noises. It also emitted this constant, periodic metallic click, like a metronome, which I was told was the clock.