{
  "patent_number": "US 3475623",
  "country": "US",
  "title": "How Robert Moog Used Transistors to Shape Synthesizer Sounds",
  "original_title": "Electronic high-pass and low-pass filters employing the base to emitter diode resistance of bipolar transistors",
  "summary": "A 1969 invention by Robert Moog that uses the internal resistance of transistors to create the iconic filters that define the sound of analog synthesizers.",
  "what_it_does": "This patent describes a method for building electronic filters by utilizing the base-to-emitter diode resistance of bipolar transistors. By controlling the current flowing through these transistors, the engineer can change the filter's cutoff frequency, which determines which sound frequencies are blocked or passed. This mechanism allows for the smooth, voltage-controlled adjustment of audio signals, which is essential for creating the expressive, sweeping timbres found in electronic music.",
  "what_it_does_not_cover": [
    "Does not cover digital signal processing or software-based filtering algorithms.",
    "Does not cover passive filter circuits using only resistors, capacitors, and inductors.",
    "Does not cover vacuum tube-based audio filtering circuits."
  ],
  "filed": "1966-10-10",
  "granted": "1969-10-28",
  "expires": "1986-10-28",
  "status": "expired",
  "holder": "ROBERT A MOOG",
  "holder_url": "https://patentbrief.org/company/robert-a-moog",
  "inventors": [
    {
      "name": "Robert A Moog",
      "url": "https://patentbrief.org/inventor/robert-a-moog"
    }
  ],
  "times_cited": 7,
  "tags": [
    "consumer_electronics",
    "mechanical"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/3475623/moog-synthesizer-ladder-filter",
  "markdown_url": "https://patentbrief.org/patent/us/3475623/moog-synthesizer-ladder-filter/md",
  "google_patents_url": "https://patents.google.com/patent/US3475623",
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}