America 250 Candidate: Negative Feedback Amplifier
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AUTOMATION HISTORY · AMERICA 250 · REPLACEMENT CANDIDATE
Negative Feedback Amplifier
American milestone: 1927 · Harold S. Black · Bell Telephone Laboratories, New York
Status: Replacement candidate. Final number pending chronology audit.
Why it belongs in America 250
Harold Black developed the negative-feedback amplifier while working in American telecommunications. Feeding a controlled portion of a system's output back to its input dramatically improved amplification stability and reduced distortion.
Connection to automation
Negative feedback became a foundation of control engineering, instrumentation, electronics and servo systems—the same general principle used to correct a process based on measured output.