| 摘要 |
An improved video amplifier arrangement with wideband D-C gain control is disclosed for use in a video display device of the type for displaying character information. The video amplifier includes an open-collector, TTL logic gate for receiving digital voice signal information which is then coupled to a cascode amplifier circuit for amplifying the video information and applying the same to a control element of an associated cathode ray tube. A D-C amplifier is provided having an adjustable element in its base input for applying a selectable D-C voltage thereto. The D-C amplifier includes an emitter resistor which is also connected to the open collector of the logic gate whereby the current developed by the D-C amplifier and applied to the emitter load resistor further determines the load current through the TTL logic gate. This, in turn, controls the level of pulse amplitude of the digital video information and serves as a video gain or level control.
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