Select switch box for white on black and black on white CRT data display

摘要

A three-pole double-throw switch is provided to selectively interrupt the video signal from an input connector to an output connector for display of white characters generated by a microprocessor on a dark screen of a CRT monitor, or vice versa, and route the video signal through an inverter for display of dark characters on white screen. One pole of the switch is used to provide the vertical sync signal to the power input terminal of the inverter, thus powering the select switch box solely from the transmitted vertical sync signal. A capacitor filters the power supply thus provided. The select switch box requires no external power and is virtually free of RF energy radiation while providing noise free data display with equal bandwidth response in both modes.