Saturday, September 26, 2020
Tube sidetrack continued
In previous item I suggested an alt-history where coherers and catwhiskers developed directly into semiconductors, or secondarily where the original Audion tube remained small and low-voltage. In those universes, experimentation would have remained easy, and real inventions would have occurred faster.
I was focusing on two separate variables, safety and size. In safety the oldest and newest eras are equally good. The tube era from 1925 to 1965 was hard for experimenters because plate voltages were dangerous. In size, the oldest era had most of the advantage. It's nice to fit your workbench into one desk, but it's nicer to SEE and HANDLE and REPAIR the devices you're working with.
Bigger things are easier to handle and repair. The latter may not be obvious to moderns.
Here's a comparison of 1918 components with moderns, more or less in proportion. In each case the 1918 is from a GenRad catalog, so it's probably a tad larger and more accessible than regular commercial parts.
Variable capacitors:
Inductors:
Potentiometers:
Rotary switches:
The 1918 components are all open, with their internal parts visible. You can clean the contacts, lubricate the shafts, and see an incipient hot spot. You can examine and fix many problems without removing and replacing the component.
The modern items are all closed and tiny. There's no way to see or fix anything. You can only replace the whole item when it goes wrong. In most real devices these components are mounted on a multilayer PC board that will be ruined if you even try to desolder and resolder, so in fact the entire board, or the entire radio or computer, must be replaced.
= = = = =
I noticed another item in the GenRad catalog that I'd never seen before:
A spark indicator. Clearly this was built from an ordinary electric fan. I can't find any GenRad manuals for it, or any pics in magazines of the time. It must have been something like a stroboscope, allowing you to see the sync-ness and shape of the individual pulses created by a typical Ruhmkorff coil with spark gap. Strobes were a GenRad specialty from the start.
Inductors:
Potentiometers:
Rotary switches:
The 1918 components are all open, with their internal parts visible. You can clean the contacts, lubricate the shafts, and see an incipient hot spot. You can examine and fix many problems without removing and replacing the component.
The modern items are all closed and tiny. There's no way to see or fix anything. You can only replace the whole item when it goes wrong. In most real devices these components are mounted on a multilayer PC board that will be ruined if you even try to desolder and resolder, so in fact the entire board, or the entire radio or computer, must be replaced.
= = = = =
I noticed another item in the GenRad catalog that I'd never seen before:
A spark indicator. Clearly this was built from an ordinary electric fan. I can't find any GenRad manuals for it, or any pics in magazines of the time. It must have been something like a stroboscope, allowing you to see the sync-ness and shape of the individual pulses created by a typical Ruhmkorff coil with spark gap. Strobes were a GenRad specialty from the start.Labels: Alternate universe
¶ 5:59 AM
