Point Contact Transistor Two Sharpened Spring Wires
# 1948 Refinement — Use Two Sharpened Spring Wires Instead of Split Foil: Naming a Choice This Series Already Made
Everything from Step 10 through Step 13 of the original construction sequence built two independent point contacts — a solder-tipped wire attached to its own spring arm, seated on its own, with the second point positioned relative to the first only once the first was already stable. That description was never presented as a choice between alternatives. It read as simply how the device gets built. This refinement, documented in 1948 alongside the original December 1947 demonstration, reveals that it was a choice all along, and names the alternative this series' own Steps 10 through 13 happened to follow: two sharpened spring wires, each independently placed, instead of a single split-foil structure carrying both contacts at once.
The split-foil wedge links the two points mechanically in a way two separate wires never do. A single piece of gold foil, slit by a razor blade into two electrically independent regions and wrapped over one plastic wedge, still shares one physical structure: the wedge's own geometry sets the spacing between the two resulting contacts at the moment the foil is cut, and any spring force applied to seat the assembly travels through that same shared wedge to both contacts at once. There is no equivalent, in that construction, to Step 11's separate spring arm for each point or Step 12's seating of one contact before the other exists at all — the two contacts are not built, positioned, or seated independently, because they were never two separate objects to begin with.
Two sharpened spring wires make every operation this series performed from Step 10 onward possible in the first place. Step 10 formed a solder drop on a single wire's point, because there was only one point to build at a time. Step 11 attached that formed point to its own spring arm, a step with no meaning if the point were instead one half of a pre-cut foil sheet. Step 12 seated one contact and verified it stable before anything else touched the germanium. Step 13 then measured and placed the second contact relative to the first, an operation this series described as impossible to perform in the opposite order — which is true specifically because the two wires are independent objects, each with its own position to set, rather than two regions of one object whose relative position was fixed before either contact ever touched the germanium.
| Step | Process operation | Input | Output | Specification | Constraint |
|---|---|---|---|---|---|
| 23.1 | Confirm each point contact is built as an independent wire-and-spring assembly, per Steps 10 and 11 | Formed points and spring arms from Steps 10.6 and 11.6 | Confirmed independent construction | Each point contact traced to its own wire, its own solder drop, and its own spring arm, with no shared mechanical structure between them | A construction that shares any structural element between the two points reintroduces the split-foil coupling this refinement is documented as an improvement over |
| 23.2 | Verify each point's position and pressure can be adjusted without disturbing the other | Independent assemblies from 23.1 | Verified independent adjustability | Adjustment of one point's position or spring tension produces no measurable change in the other point's position or tension | A shared structure that couples the two points' positions defeats the purpose of building them independently in the first place |
| 23.3 | Document which construction method — two independent wires or a single split-foil structure — was actually used for this device | Verified construction from 23.1 and 23.2 | Documented construction method | Method recorded explicitly, since the device's later spacing and pressure specifications in the next refinement depend on knowing which method produced it | A device built one way but documented as if built the other way misattributes its later spacing and pressure measurements |
This refinement does not change how this series' device was built; it names the choice that building already made. Every operation since Step 10 assumed two independently placeable, independently tensioned point contacts, and this is the step in the historical record that explains why that assumption was reasonable — because it describes the actual alternative, split gold foil on a single wedge, that the original December 1947 demonstration used and that this refinement moves away from. The next refinement in this sequence gives the spacing and pressure this construction method makes possible an actual, documented number.