One not so recent project completed was a game of oscilloscope pong. In a small group a game of pong was built with an oscilloscope serving as the display. This was all run on an FPGA development board with a minimal of external hardware.
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The oscilloscope was controlled in xy mode and the z input was used to modulate the beam strength. Using this, both the text and game screens were shown. All of these oscilloscope inputs were feed input from the development board pwm outputs. These were each passed through one passive low pass stage to smooth out the signal. The z input was feed directly from the development board sending high for beam off and low for beam on.
External circuitry was used to generate sound effects, which are not shown in the video. The sound circuitry consisted of a Wein Bridge RC oscillator. The oscillator was toggled with one transistor in the feedback path.