Abstract: An RGB video output drive amplifier is provided with current limiting circuitry at the base of the driver circuit. In a preferred embodiment, the driver circuit comprises a drive transistor with associated biasing circuits. The base of the drive transistor is coupled to a current limiting circuit to shunt excess current from the base of the transistor and to block additional input current at or near the level representative of the driver transistor reaching its saturation mode. Excess current is dissipated through associated resistance in the base circuit and while diode means prevent high input signals from driving the drive transistor into saturation. Maintaining the drive transistor at or below its saturation level pevents flaring in the resulting video picture display. No appreciable storage charge is built up during the short periods which the drive transistor may enter saturation in response to rapid transients provided through a transient response circuit in parallel with the current limiting circuit.

Abstract: An integratable amplifier is disclosed for developing a high level output signal with reduced power dissipation. The amplifier includes a first circuit (108, 110) which responds to an input signal for developing first and second signal currents whose amplitudes increase and decrease, respectively, in response to an input signal transition of a given direction. A second circuit (32a) receives the first signal current for establishing a third signal current which mirrors the first signal current. The second and third signal currents are received by a third circuit (70a) for conversion thereof to an amplified output signal. To stabilize the gain of the amplifier, a negative feedback path (50a) is coupled between the input signal and the output signal.

Abstract: An integratable CRT spot cut-off network is described for use in a television receiver. The network establishes a reference current for biasing up the receiver's G.sub.1 grid when the supply voltage comes up, and a bypass capacitor coupled to the grid charges toward the supply voltage. When the receiver is turned off, the network terminates the reference current as the supply voltage starts to collapse and prevents the bypass capacitor from discharging. The charge stored on the capacitor reverse biases the grid to cut off the receiver's beam current.

Abstract: A stabilization network is disclosed which compensates for variable emission characteristics of a cathode in a television receiver's cathode ray tube. During the receiver's vertical interval, a variable gain video amplifier applies a black level D.C. voltage to the cathode. The resulting cathode current is sensed and compared to a low level reference current. If the cathode current does not equal the reference current, a control signal is applied to the amplifier. The amplifier responds to changing its D.C. output voltage until the cathode current is equal to the reference current. The amplifier also responds to the control signal by altering its gain so that, when a video signal is received, the cathode develops peak white currents of a given value in response to peak white portions of the video signal.

Abstract: A circuit is disclosed for establishing proper video output voltages in a color television receiver prior to setting the receiver's G2 voltage. In the preferred embodiment, the circuit includes three emitter follower stages, each coupled to the output of a video amplifier. The collectors of the emitter follower stages are coupled to a supply voltage through a common resistance. A two position switch is connected across the common resistance such that, during normal receiver operation, closure of the switch shunts the common resistance. When G2 set-up is to be effected, the switch is opened so that a predetermined voltage is dropped across the common resistance and the three emitter follower stages have similar, predetermined D.C. output voltages.

Abstract: A service switch arrangement for a color television receiver having a low level matrixing system developing red, blue and green color signals includes a service switch having a normal position and a service position. In the normal position of the switch, a video output amplifier is enabled for coupling the red, blue and green color signals to the electron gun cathode elements of a color cathode ray tube. In the service position of the switch, the video output amplifier is disabled while an independently generated DC control voltage is coupled to the electron gun cathode elements for facilitating adjustment of the cut-off points of the cathode elements.