1524715 Gain control RCA CORPORATION 30 Oct 1975 [6 Dec 1974 25 Aug 1975] 44953/75 Heading H4R The gain of a (chrominance) signal appearing at a first transistor input stage 24 associated with a quiescent current source (resistor) 30 is controlled by varying the current division ratio between a second transistor 32 with load impedance 36 and an impedance-variable semiconductor rectifier 34 D.C. coupled to potential divider 42, via a third transistor 46 and a resistance 52 (and possibly 19). A parallel circuit 25, 33, 35, &c., produces an output at 41 in antiphase to that at 40. Saturation and luminance control is effected by potentiometers 13, 14 and a light dependent resistor 15 may be inserted to adjust luminance according to ambient light conditions.
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