To quickly test my latest monitor I programmed my PICxie box to output a test card pattern to an ultra bright LED.
The idea is you can hold it behind a new disk/drum to get an idea of what the final monitor will be capable of.
My PICxie box has a potentiometer connected to an analogue input and this is used to vary the frame rate so that I can just run the disk/drum motor off a fixed supply (i.e. no with sync)
I think such a tool could be built to look like a sonic screw driver! LED one end, frame rate knob the other. There could even be a multi-position switch on the side to select a test card!
A PIC can easily do this and could even do greyscales (or perhaps RGB).
Has anyone ever wished they could reach for something like that?