Two-speed automatic phonograph

Details Two-speed automatic phonograph Two-speed automatic phonograph

1975-04-18

1977-01-04

Aegerter, Richard E.

Undertaking

274 39A, 318166, 318168, 318171, G11B 2504

Patent

active

040009068

ABSTRACT:
A two-speed automatic phonograph has a self-resetting, record-centering pilot to receive records having different size apertures therein. The records of different size apertures are to be operated at different playing speeds for reproduction of the sound tracks thereon. The speed at which the record is turned, i.e. 331/3 rpm or 45 rpm, is automatically controlled by sensing a characteristic of the record to be played. This will vary the frequency of a signal source which controls the speed of rotation of a synchronous motor which drives the record turntable at the proper playing speed. Also, the motor drive circuit includes means for applying a high voltage to the motor during startup thereof and for reducing the voltage applied to the motor during normal running while a record is being played.

REFERENCES:
patent: 2505630 (1950-04-01), Weathers
patent: 2885208 (1959-05-01), Pranter
patent: 3193296 (1965-07-01), Rockola
patent: 3416057 (1968-12-01), Froyd et al.
patent: 3463986 (1969-08-01), Curriston et al.
patent: 3485499 (1969-12-01), Fukuda
patent: 3599984 (1971-08-01), Kondo
patent: 3814442 (1974-06-01), Van Antwerp
patent: 3819992 (1974-06-01), Opal et al.
"Electronic Drive" Radio-Electronics p. 56.

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