EZVideo2oscilloscopeV1

The goal of this project was to display video on an oscilloscope without the requirement of external Z modulation input.

As for accomplishing the goal, the project is a major success as the resulting video converter allows to display the converted signal on an oscilloscope without the need for a Z mod input, as well as without the need for X input, since the X ramp/sweep is generated by the already present time base which is triggered by video sync pulses.

The principle lies in using a PWM square wave superposed onto a vertical scan ramp which results in two drawn fields stacked on top of each other. The bottom field is the primary output image and the upper field happens to be the inverted image (blacks are white and vice versa) of the bottom field, which is caused by the principle of using PWM to make the trace stay at the lower field when a white is desired, or having the trace jump to the upper field when a black is desired. By changing the duty cycle of these jumps the perceived brightness of the trace can be continually changed, just as modulating the cathode current in the CRT would, only in this case it remains constant.