Recording current control circuit for video recorder head system - has transistor switching device adjusting image carrier amplitude for alternating image half frames

摘要

The circuit uses a switching device (T1) in the signal path to the magnetic recording heads (K1, K2) supplied with an image carrier (BT) which is frequency modulated with the light density signal (Y) and a quadrature modulated colour carrier (C) via a rotary transformer (Tr) with two primary windings (P1, P2) and two secondary windings (S1, S2), across which the recording heads are connected. The recording heads are used to record respective half frame images in alternation, along a helical recording track. The switching device is used to switch the amplitude of the image carrier for each half frame to obtain a similar current in each magnetic recording head. Pref. the switching device uses a transistor supplied at its base with a switching voltage (Vs) with half the image frame frequency. The transistor may be integrated in the head amplifier circuit. ADVANTAGE - Simple integration in head amplifier integrated circuit for eliminating differences between recording heads.