FWIW, I'm starting to work on a version that uses an off-the-shelf MCU board, so no assembly is required other than connecting to the vertical and horizontal of a scope, and powering the board (via a USB connector).
And my intent is to make a Windows console app that processes an arbitrary BMP image, and talks to the MCU board via USB to load the 'image' into the board for display. So the image can be changed at any time.
This morning I did a "proof of concept" to verify that I can control multiple analog outputs from the MCU board. The output voltage is 0 to 3.3. The 'bandwidth' of the output has limits - basically a slew rate limit. So small changes in the output are fast, but large step-function changes show some 'rounding'. But it seems to be plenty fast for a CRT display.
The "catch" is (of course) that the rest of the firmware/software still needs to be written... ;-)
The board I'm using is this:
It's only $13 from T.I. I've used this board, and many similar T.I. boards, on various projects (and in my "real job" at HP before I retired). It supports four analog DAC outputs, so I'm thinking that I can support X, Y, and Z axes on a scope.
It implements a USB "console" port, which is easily discovered by Windows as a COM: port. I assume that other OS platforms would do it also. The 5V on the USB port also powers the entire board.
In the SW, my first thought is that a raster display would be easiest (given that a BMP file is the input). And with Z-axis intensity control, it would probably make nice displays of detailed images(?).
But a vector display would also have advantages (more like what the VintageTek board does). Needs more thought...
For a case that does NOT include the Z-axis, I'm thinking that a 'hybrid' of raster and vector would be an easy thing to try: that is, with a monochrome image, the dot moves very quickly over the 'black' parts of a scan line, but 'lingers' on the 'white' parts.
Anyway, if/when I come up with anything that works, I'll be glad to share it.
Pete
saipan59 (Pete)