I really appreciate the information. Another question...If I want to design a clock using a 7 segment VFD tube can a clock design using standard 7 segment LED's be adapted to drive the VFD tubes. I know the voltages for the plate, filament and grid drive circuitry are different but I am talking about the logic from the PIC microcontroller or whatever the LED design was using. If I used an existing microcontroller that was programmed for a seven segment LED clock would the same firmware work for driving the 7 segment VFD tubes or are there timing issues that would be a problem? I understand there are dedicated VFD driver chips available. Do they use BCD inputs as a LED 7 segment clock would use.....thanks again for your extremely helpful information..
Regards Robert W8UUU On Aug 14, 6:52 pm, threeneurons <[email protected]> wrote: > | Can anyone recommend ... information to get me started. They > | seem to be like regular triode tubes but driving them seems sort of > mystical > > Here's a nice little primer from Noritake: > > http://www.noritake-elec.com/vfd_operation.html > > Basically, the same info I read from one of their databooks, in the > early 80's. Yep, they are directly heated triodes, with a different > purpose. The filament voltage is kept low enough, so that they don't > glow. The anodes are painted with the phoshor, and glow when hit by > electrons. Anodes are also called segments. A positive voltage is > applied to the grids (relative to the cathode [filament]) in order to > get conduction, but a negative potential (~-5V) is applied to ensure > that they are truly OFF. Grids are often used for multiplexing, in > multidigit tubes. To light one up. Apply a positive voltage to the, > selected digit's, grid and the segments (anodes) that need to be lit. > Voltage ~50V, in multiplexed apps. Anode current is usually in 100s of > mircoamps range, but the grids can draw a few milliamps. Grids drawing > current is something usually only seen in power triodes, but that's > due to the positive potential. > > Nothing really too mystical about them. I like using two "like" > technologies in a clock like application. For example, adding a > dekatron, as a pendulum, in a nixie clock. Both neon. For a VFD > project, how about mixing an eye tube with it. Use one, or two, as a > colon separator. Eye tubes like an EM80 or EM84, usually need a plate > voltage of 200 to 250V. They, however, only use about 3mA. Build a > switcher that outputs 50V to 60V, then add a simple multiplying ladder > (of 1N914 diodes, and low value caps; 0.1 to 10uf) to get eyetube > voltgage. > . -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
