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Thread: Vacuum Fluroescent Display (VFD)

  1. 12th January 2004 12:40 AM #1
    Johnson777717
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    Default Vacuum Fluroescent Display (VFD)

    Hey folks!

    I'm trying to figure out the pinouts for a VFD (Vacuum Fluroescent Display). Display has 12 characters, 7 segments each character.

    I've been messing with this thing for an hour or so, trying to figure out which pins are positive, and which are negative etc.

    Here's my questions:
    1. I see from the back of the VFD, that the two outside pins are positive, one on each side of the VFD. So, if I apply positive to these pins, and negative to the other pins, I should get some sort of light from the display? Right? Am I missing another positive pin?

    I suppose that I'm a little confused about the way these work because I am missing a connection in order to light a segment. Once I find out how to light a segment, I can trace the circuit and figure out the other segments. Does anyone know what I need to do in order to get at least one segment to light up?

    Thanks for your help and your time! Have a great one!
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  2. 12th January 2004 01:35 AM #2
    Eclipsed
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    VFD's need rather large amounts of voltage to work and are rather complicated to control.Check out www.Maxim-Ic.com they have controller chips and driver chips.
    Eric.
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  3. 12th January 2004 03:23 AM #3
    k7elp60
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    Default Vacuum Fluroescent Display

    I have found that they work just like a vacuum tube. They have a heater/or filament. Contol grids and anode's for plates. I have built several digital clocks with them that ran off of 12 volts. The filament is a thin wire that goes bach and forth between the two ends of the display.
    The grids look like a very small window screen and they generally cover one digit. The anodes are the individual seven segments, and they are usually mutiplexed together. The filament usually takes several hundred Ma at a low voltage. The ones I have used I have been able to look thru the face and see the wires for the filament the grids and many times the
    anodes or segments.
    The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
    Show me a different way. I have an open mind.
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  4. 12th January 2004 06:41 AM #4
    Someone Electro
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    So thats what the strange displays are caled. I have one laying around unused.I to cant get it to light up.

    On the back side it seas.
    NEC FIP11SM7 NO. 421-421 JAPAN

    Its from a wery old VCR and i cant find anything abaot it.
    The flagment is ok (The resistane is 8 Ohm).I dont know what voltege it neads.It worked on the VCR before i tocke it a part
    Il give you shocking experience.
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  5. 12th January 2004 03:01 PM #5
    Johnson777717
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    You guys are awesome! Thanks!.

    After posting my questions, I did some research and found what K7EL explained.

    The displays that I have, you can see all of the different connections for the Anodes, the grids and the filament. The tricky part is finding the connection on the other side of the VFD. I know the filament connections are the two opposite-outside pins. I applied ground to one pin, and 4.5V to the other, and thus made the filaments glow! :shock:

    http://www.atip.org/fpd/src/tutorial/fpd.html
    This site explains that the filament is the cathode (Negative) and the grid and the anodes are positive. (Look at the diagram about 3/4 way down the page.)

    Now all I have to do is map the pins. Once I figure this out, I'm posting this son of a gun somewhere where people can find out about the pinouts!!!
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