Ampex Corporation

Guzik Technical Enterprises

James W Jones

Nahum E Guzik

Alan G Grace

Gennady Mangeym

Walter J Cheney

The present application discloses an electronic switching device in combination with a low noise, low input impedance preamplifier circuit. The resulting electronic preamp assembly is specifically configured so that it can be directly interchanged with existing mechanical relay/preamplifier assemblies such as those presently in use in recorder/reproducer apparatus having dual function record/playback heads, without disturbing the associated operating parameters of the record or playback channels. The electronic preamp assembly includes a balun transformer and a solid state switch coupled from a record amplifier to the record/playback head via a rotary transformer to define the record channel. The playback channel includes a diode bridge switch and a preamp circuit also coupled to the rotary transformer and head. The playback channel is electrically isolated from the record channel, and vice versa, via the solid state switch and diode bridge switch in response to a select play/record mode signal applied thereto.

Electronic record/play switch with low noise low input impedance

A motor speed control system comprises an encoder (12) which produces a series of indicator pulses related to the motor's speed. The period of the pulse is compared with that of a crystal-controlled reference period produced by a period generator (14). Comparison is made by means of a period comparator (16) consisting of logic elements, including flip-flops (F1, F2, F3) and gates (G1 and G2). Digital outputs of the period comparator control UP and DOWN charge pumps whose integrated value controls the motor through a power driver. Advantages of the system are precise digital control with crystal accuracy.

Motor speed control system

A magnetic disc has a plurality of video track segments for storing distinct fields of video information. A look-up track is provided on the disc and segmented to store indirect address data which may be represented by random numbers, and which are related to the video information fields. Both the look-up track segments and the video track segments are numbered sequentially. Each video track segment is permanently associated with a look-up track segment. A movable transducer is associated with both the video tracks and the look-up track. A counter circuit is provided to indicate periodically the instant look-up segment numbers with respect to the instant position of the rotating cyclical storage device and in synchronism therewith. A first comparator circuit compares an indirect address input request with the indirect addresses recorded on the look-up track. Responsive to an output from the first comparator circuit, a buffer circuit stores an instant look-up segment number and transfers it to a control circuit. A control signal from the control circuit is sent to a transducer positioning device which moves the transducer to the corresponding video track segment. A look-up decoder circuit is designed to sense a first empty segment automatically and periodically. A new video picture information is stored on the video track segment corresponding to that first empty look-up track segment. Data bits are stored on the back porch of the horizontal sync pulses on consecutive lines of the video information. A circuit is provided to extract these data bits and restore the look-up track if accidentally erased.

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Woodside, CA, United States of America

James W Jones