On Friday, February 8, 2013 7:22:47 AM UTC-6, jrehwin wrote: > > > You are multiplexing this display on a "one of six" basis. That means > each nixie tube is only going to see juice for maybe 15% of the time. Even > if you overdrive them, they will be on the dimmer end of their possible > light output, and I would imagine that for your application nice, bright > displays are somethiung of a prerequisite. You might want to consider > designing the mux to be two sets of "one of three". > > Unfortunately, this is what the pinball machine provides to the display - > BCD code for the current digit, and six (or seven) digit select lines. > Getting around this > would require a great deal more in the way of semiconductors. > MrNixie - John is correct. The "one of seven" drive is the requirement of the pinball machine design. These displays are intended to be "drop in replacments" I'm thinking in "practice" It might be safe to latch the anode address at the same time the bcd digit is latched so that the displays can be on longer. But this is a Rev2 or Rev3 design if I ever get to it. <<I do feel that you may have over complicated the LED drivers a little bit. Seems like an awful lot of semiconductors in there!. First of all, consider wiring pairs of LEDs in series, or even quads in series, depending on what (12V?) power supplies you have to hand. Then current limit them through a series resistor, and wire multiple strings of this arrangement in parallel and then back to just the one switching transistor.>> No 12VDC supplies are brought to the displays. We only have 5VDC and 190VDC comming in. I don't want to put the LEDs on the 190V display because it is a realitvely small current supply (or will be on my machine.) I don't want a boost converter to bring 5V to 12V either. I think for this application; the existing implemenation is proably the best.
<<The resistors R56/R57 in your anode drivers are probably a bit low - you've got the best part of 2mA of (expensive) HT flowing down there. The driver transistor q21 etc. won't need that much base drive. I've used values three times yours before, without any issue or ghosting, etc. >> Yeah; I wasn't sure about the 12.5K Anode resistors. They calculate fine; but agreed that 12.5K seems low. For my initial proto; I have a 50k pot attached to A1... so I can vary the resistance til I get a reasonable display. My calc was roughtly: 190V-170V-(2*0.3) / 2mA ~= 12.5k <<I think 190V HT may be a bit too "hot". You may find the displays will work fine at 180V, even 170V. The tube's actual striking voltage is probably around 150V. You will need to set the anode current limiting resistors to suit, of course.>> Again; limited by "drop in" design to existing display. 190VDC is the incomming PSU rail for a normal display. It's 190+-5Vdc. <<Zitt is wrong in saying Xenon had nixies instead of the usual VDF displays. Bally never used VFDs (but Gottlieb did). Xenon never had any nixie tubes either, nor did any US production pinball machine. The French Rally Plays are the only nixie tubed pinball machines. Maybe Zitt remembered a mod someone else had already done? >> Correct; I wasn't clear. AFIAK no volume pinball machine used Nixie displays. The XENON I saw; was a modded XENON at TPF. Not stock. -- 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 [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/1f7ONFtN8WMJ. For more options, visit https://groups.google.com/groups/opt_out.
