Oscilloscope clock

From MAKE Magazine:

Frank made the coolest clock, ever. He writes - A while ago, while surfing the web I found an interesting idea for an oscilloscope clock. I have spend some time thinking about it first, and finally decided to make one myself. First I made a crappy version with a R2R resistor ladder network for a DAC to test the idea. The next improvement was to use a real DAC that works a lot better. The results were so good that I decided to make this project available as a kit. The idea is to display a working clock on the surface of a CRT tube as used in most oscilloscopes. It's not easy to find large numbers of identical CRT tubes, so I only made a kit that provides the x-y signals. You can connect this kit to any oscilloscope that supports x-y display. Practically any two-channel oscilloscope can handle that. There is no need for Z-modulation (intensity of the beam) as the trace moves very fast between the various parts of the picture. Credits go to the fast settling dual DAC, the most expensive part of the design. The image is very crisp, but remember to put the input channels in DC mode for the best result.

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