Abstract: An automatic vertical display change circuit for a monitor includes a transistor that is operated in response to a mode signal for determining the amplitude of the vertical ramp produced by the vertical oscillator. The transistor is driven conductive to load the voltage supply means for the oscillator and reduce the operating voltage therefor to decrease the vertical ramp amplitude.

Abstract: A dual intensity video highlight circuit for enabling a maximum brightness display on a CRT includes a cascode connection of a video output transistor and a video driver transistor with the video driver transistor having a pair of series connected resistors in its emitter circuit. A character generator supplies pulse signals of different amplitudes to the video driver transistor, which inverts the signals. The inverted signals are amplified by the video output transistor and supplied to drive the CRT. A video intensifier transistor has its emitter collector junction connected across one of the emitter resistors for shorting out that resistor, responsive to a control signal, for changing the gain of the video output transistor to permit a maximum brightness display for highlighting.

Abstract: A monostable multivibrator provides accurate control of a timed output signal relative to an input pulse provided thereto. A pulse width control circuit of the multivibrator having a variable resistor is coupled to an RC circuit for controlling the extent to which a capacitor therein is charged without affecting the circuit's RC time constant. The rate of discharge of the timing capacitor thus remains unchanged resulting in a substantially constant discharge slope over a range of time delays. In addition, the duty cycle of the multivibrator may be varied over a wide range by merely changing the value of a single resistor therein which also does not affect the discharge rate of the multivibrator's timing circuit and thus does not introduce unwanted variations in the timing of the output pulse.

Abstract: In the horizontal drive of a raster scanned video display, a free running astable multivibrator responsive to a synchronization input signal provides a horizontal output signal to horizontal deflection circuitry for synchronizing the video display's raster scan with the video information presented thereon. The astable multivibrator includes a pair of coupled transistors which are alternately rendered conductive in accordance with the time constant of a respective RC network associated with each transistor. To compensate for the temperature-dependent operation of the transistor pair which causes the multivibrator's operating frequency to increase with increasing temperature, a pair of back-to-back coupled diodes are connected to provide the synchronization input signal to one RC network so as to increase the charge on a capacitor within the network, the time constant of which is similarly increased. The temperature-dependent change in voltage across the diodes compensates for the change in V.sub.

Abstract: A system for increasing synchronization signal injection to a free-running multivibrator in the horizontal drive circuit of a video display which enhances synchronization signal frequency capture range is disclosed. A reduction in synchronization input signal amplitude due to an input signal voltage cutoff threshold which reduces spurious multivibrator inputs is compensated for by coupling the multivibrator synchronization input signal to the emitter and collector of both of the multivibrator's coupled transistors.