One more idea. Sorry for posting so much but I think it really is an interesting clock!
The thing that bothered me a bit was the fact that previous circuit generates so many interrupts. At the moment you need to display multiple circuits for a specific arc, the amount of circles required is dependent on the size of the circle to make it appear at the same brightness as the other arcs on the screen. This requires a quite high circle frequency (about 38kHz) as some circles need to display maybe 5 times and others 20 times. Suppose there is a way that you can always use just 1 circle, and it will always display as bright as others independent on its size. If that was so, you can significantly reduce the frequency and reduce the amount of interrupts at the same time. Probably divide by 8 (around 4.5kHz). Secondly you could go to 60 segments rather than my initial 120 which gives you a larger interval between 2 subsequent segments. The interesting thing is, you can actually do this relatively simple. You could take a second MAX509 DAC and hook it up parallel to the first one. Then you use POS5A for inputs REFA and REFB. The outputs OUTA and OUTB will give you information about the size of the circle currently displayed. If you invert these voltages and summarize them ((POS5A-OUTA + POS5A-OUTB) amplify them and make them negative, then you have a voltage for the control grid Ug1 = A (OUTA + OUTB - 2POSA) which automatically adjust the brightness according to the size of the circle. Sure this is not perfectly linear but it will closely represent the correct brightness. Michel -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
