Hello. I'm pretty new to nixies/vfds, and I have some questions on how to drive a VFD tube before I pick some up on ebay:
1) If the filament needs 1.5v at 0.02A, and I'm driving with 5v, would I just do (5-1.5)/0.02 to get the resistor value? 2) For the same filament, if I have a 1.5v source, am I safe to drive it without the resistor? 3) I read that the grid needs a negative voltage to make sure all the segments are off. Is this true? I've seen some circuits where they just bias the filament voltage a bit higher with a diode or a resistor before the ground. Does that work? Is this what the max6931 filament bias does? As in I supply -7v to the IC, and drive my filament between 0-1.5V, and the IC would switch between something like 30V when things are on and -7V when things are off so that it is negative of the cathode voltage? 4) Why do some circuits bias the filament at a negative voltage like -30v? 5) Do I need current limiting resistors at the grid and anodes? 6) If I'm not using a driver IC, and I want to control the gate/anodes using some mosfets, what would be the best way to do it? Would I do something like this http://cnx.org/resources/8fb47c89fd6fbc28ff5e2699eb54c529ee279f9c/4.35.png or would that resistor impact performance? 7) Is it safe to leave grid/anode pins floating? 8) If I drive one segment more than the other segments, would it "wear out"? Kinda like cathode poisoning with nixies? 9) What contributes more to tube life? Less filament current, or lower grid/anode voltages? Is it both? 10) What is the mechanism in which VFDs fail? If I don't drive them out of spec, are they "immortal" like LEDs are, or does turning them on consume some sort of material inside that puts a timer on their lifespan? I'm just curious that if I leave a VFD clock on, and it's rated for 2000h or something would it fail in a few months? 11) If I want to dim the VFD, do I pulse the grid or do I pulse the filament? Thanks for the help! -- 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/msgid/neonixie-l/6310577f-967b-44d8-a736-c3467979b240%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
