Re: ICE TUBE Second digits are DIM
neutron spin, I appreciate your input, and I will admit that fixing this in software is not an ideal solution. However, given the hardware constraints it is the most practical way to solve the problem. The gradient on mine is not a gradual decrease in brightness from left to right, but rather all digits are bright and perfectly readable, except the last. With the default adafruit firmware, I could barely read the digit at 50% brightness even in a dark room. Obviously the situation was even worse in a lit room. The display needed to be turned up to 90% for readability. That is not a usable state. This simple fix has helped make the clock more usable, and more aesthetically pleasing. If it shortens the lifespan of that digit, so be it, I could barely see it at all before this hack, so what am I losing?
wbp, thank you very much for your suggested changes to the code. I am a hardware guy, not a software guy and your code helped a lot as a good starting point. The fix works quite well, and I can bring the last digit up until it is just barely dimmer than the second to last digit. I do have to display it for more than one extra cycle though! Displaying it 3 or 4 times for every display cycle seems to do the trick. I suppose I got unlucky with the tube I got, a combination of bad tolerances added up. I think I may attempt to refine the solution further changing the timings of the refresh rate and perhaps changing the order of the digit display, interleaving the last digit displaying with the others. Such as 0,1,8,2,3,8,4,5,8,6,7,8. That way instead of simply displaying the last digit longer at the end, it is displaying it more frequently. Not sure if the overall effect would be better or not.
I did not mean to stir the pot so to speak. I simply had a last digit that was so dim I could barely read it, and wanted to attempt some way to improve it to a more usable state. I may also attempt buying a few spare tubes and adafruit tube PCBs and headers. I agree with neutron spin that this may shorten the lifespan as it effectively doubles or triples the amount of on time for that digit only. I am not sure what contributes to loss of phosphor efficiency exactly, on time, loss of vacuum, or diffusion of impurities in the phosphor are all candidates I suppose.