# L Blackwell — Patents explained on PatentBrief

L Blackwell has 1 landmark patent explained in plain English on PatentBrief.

- [How Vacuum Tubes Detect Tiny Changes in High-Resistance Sensors](https://patentbrief.org/patent/us/3735375/smoke-detector-ionization) — granted 1973
  A 1973 circuit design using a vacuum tube to detect microscopic resistance shifts in sensors like ionization chambers, commonly used in early smoke detectors.

**Full profile:** https://patentbrief.org/inventor/l-blackwell

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_Source: PatentBrief — https://patentbrief.org. Plain-English explanations of US patents._