Just wondering what you use to clean the flux off the board? I have one of your kits and have tried all other suggestions, resistor substitutions etc. for getting rid of ghosting with no real success. I love the clock and all it can do but the ghosting is a little annoying.
Thanks... On Thursday, February 11, 2016 at 8:22:11 PM UTC-5, threeneurons wrote: > > Well I'll go to the end, with the solution ... Clean your Boards !!!! > > Back to the beginning. I'd been selling some multplexed nixie kits for > close to a year and a half, now. It uses a unique form of multiplexing > called "Charlieplexing", invented at Microchip. There it was used for > driving LEDs. A clever member of this forum (when it was back at Yahoo), > named Jason Harper saw that it could also be used to drive the base-emitter > junctions of transistors, back ~2003. For our pleasure, base-emitter > junctions, of HV transistors. In short, charlieplexing nixie tubes. That's > what I incorporated in my kit. > > One important issue with charlieplexing, is that it can only be done with > uC tri-state I/O bits. It needs the I/O bit to not just output a one (1) or > zero (0), but also present a high-impedance (Hi-Z). With charlieplexing, > only one "node" (p-n, or base-emitter junction) of its matrix can be active > at any time. One output issuing a "0", while another issuing a "1", with > the rest "inactive" and presenting their Hi-Z state (DDR bit set to > "input"). This becomes a key to the problem later. > > Multiplexing, in general, and not just charlieplexing, can exhibit a > problem called "ghosting". This is when more than one numeral appears to be > ON at any time. Usually, the intended numeral is on brightly, while a > second numeral is only slightly glowing in the background. Hence the term, > ghosting. It can have multiple causes, that usually boil down to something > being ON at the wrong time. A timing issue. This isn't an issue with direct > drive displays, since they don't rely on timing. > > Now to the problem at hand, and its inadvertent solution. A customer > returns a board (for evaluation) on what's causing his ghosting problem. I > turn it on to confirm the problem ... yep, ghosting. Pretty severe, too. I > examine the board visually, but all the parts are in the right place, and > the solder joints look okay. So, before probing around further, I decide to > clean off the flux residue. When I'm done, I let it dry for a half hour, > before applying power. Turn it On ... no ghosting. Apparently, the flux > residue (and whatever contaminants it trapped) was conductive enough, to > turn ON, inactive "nodes" (transistors). > > In conclusion, clean the flux residue off the board ! > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2aa06848-7851-43a7-8f86-e44ef09cb464%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
