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Re: [smartsockets] A couple of B7971 board questions

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  • Ray Fenwick
    Hi there. Do any of you guys fancy posting some pictures? I fancy a kit myself... Many thanks Ray
    Message 1 of 7 , Apr 28, 2008
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      Hi there.

      Do any of you guys fancy posting some pictures? I fancy a kit myself...

      Many thanks

      Ray

      On 28 Apr 2008, at 04:57, Brett Paulin wrote:

      > I just finished building my Smartsockets and got them fired up
      > yesterday - :)
      > Wow, B7971's are *big*..
    • Quixotic Nixotic
      ... Well Ray, the boards do what they say they will do. They are good! I used crimp connectors from D sockets for my tubes, soldered to the smartsocket PCBs.
      Message 2 of 7 , Apr 28, 2008
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        On 28 Apr 2008, at 10:35, Ray Fenwick wrote:

        > Hi there.
        >
        > Do any of you guys fancy posting some pictures? I fancy a kit
        > myself...
        >
        > Many thanks
        >
        > Ray
        >

        Well Ray, the boards do what they say they will do. They are good! I
        used crimp connectors from D sockets for my tubes, soldered to the
        smartsocket PCBs. They worked just fine.

        I just uploaded my files for my clock to the files section, in a
        folder called John's clock. Pictures of the built unit are in the
        pictures section.

        I have uploaded:

        1] My very simple circuit diagram. I knocked it up in no time on
        Veroboard. It's up to you how you generate your high voltage for the
        tubes. I used the back-to-back twin transformer method.

        2] A list of four letter words to burn to i2C EEPROM - a 24AA512.
        This is a list of all the allowable English four letter words in the
        board game of 'Scrabble'. No I haven't heard of a lot of them either.
        3,539 four letter words in total. Yes the rude ones are all in there.
        There is no profanity setting, just switch the clock off when the
        prurient are visiting. My sister is an ordained minister and so far
        it has failed to say anything abusive in her presence, thank dog. At
        other times it has been hilarious when it says something seemingly
        appropriate...

        3] PicBasic code for the clock (there are some comments in there of
        how it works)

        4] Hex code to burn a 16F628a PIC for the clock.

        If anyone wants to build this clock, I can supply a burned PIC and
        EEPROM set.

        The clock is not 100% as I would like it and I keep meaning to
        revisit it and tidy up the editing etc., and add some UDCs (user
        defined characters) and animations, which is why I haven't posted my
        gubbins before. When I do this I will upload new code and make it
        available.

        In operation the clock tells the time every minute for a while. The
        rest of the time it is displaying random 4 letter words. The fade
        effect changes every now and again. I can't remember just when, but
        look in the PicBasic code and you can probably work it out.

        Best wishes,

        John S
      • Brett Paulin
        ... OK, You asked for it.. Family Photo :) - I hope noone minds attachments on the mailing list - B7971 s in Smartsockets, IN4, IN8, IN12 in
        Message 3 of 7 , Apr 28, 2008
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          > Do any of you guys fancy posting some pictures?
          > I fancy a kit myself... Many thanks
          > Ray

          OK, You asked for it.. Family Photo :) - I hope noone minds attachments on
          the mailing list

          - B7971's in Smartsockets, IN4, IN8, IN12 in SmartNixie-Socket, IN13 Tube

          Sorry about the low-res, its a camera-phone. I'll make some better ones when
          they get nice cases to live in and are worth photographing :)

          Kits arent usually worth it for low volume producers - Smartsockets arent too
          hard to source the parts for yourself - Building them took more time than
          finding the parts.

          Onno has the Micros, PCB, Sockets and Tubes available here
          http://www.tromop.eu/cms/index.php?option=com_content&task=view&id=24&Itemid=40
          which just leaves you the resistors, transistors and connectors to find.

          My Liquid Neon Tubes arrived today, wait till you see what I have in mind for
          the next Smartsocket ! :)

          regards

          Brett
        • Onno
          Terry, The connectors and headers i m using right now came from Farnell. Header: 9731636 MOLEX 22-05-7058 Connect: 146256 MOLEX
          Message 4 of 7 , Apr 28, 2008
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            Terry,

            The connectors and headers i'm using right now came from Farnell.

            Header: 9731636 MOLEX 22-05-7058
            Connect: 146256 MOLEX 22-01-2055
            Pins: 9773789 MOLEX 08-50-0032

            Grtx,
            Onno
          • Chris
            ... yesterday - :) ... be to ... dont ... an ... Hello, If the datasheet for the B7971 s is to believed then the different lengths of the cathodes lend
            Message 5 of 7 , Apr 29, 2008
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              --- In smartsockets@yahoogroups.com, Brett Paulin <yahoogroups@...>
              wrote:
              >
              > I just finished building my Smartsockets and got them fired up
              yesterday - :)
              > Wow, B7971's are *big*..
              >
              > I just used a link for R31, since I'm running at 170v.
              >
              > If your power supply is not adjustable, then the accurate way would
              be to
              > meter the current and choose a resistor accordingly, although I
              dont
              > quite "get it" as to how a single anode resistor can be accurate if
              an
              > unknown number of cathodes are illuminating.



              Hello,
              If the datasheet for the B7971's is to believed then the different
              lengths of the cathodes lend themselves very well to approporiately
              chosen resistors in the standard values series.

              Not sure if that was the intention or if that's how it worked out,
              but to clarify , you should choose the resistor value for the cathode
              resistors to get you as close as possible to the desired current
              values for your device , ZM1350 or B7971. However you may be slightly
              out even then , and the voltage from the supply a little high still,
              in which case adding a small amount of anode resistance, used just to
              trim the final voltage, can be used. It was probably overkill on my
              part to include it, but I felt that for all the time and effort it
              takes to be able to quickly add a bit of resitance or possibly even a
              fuse it was worth including.

              In a test I did with a 200V supply I found that when comparing one
              tube with the the resistors for 170V plus a small anode resitor,
              against a tube with reistors for 200V and no anode resitor, there was
              only a very slight difference in the apparent brightness of the
              cathodes regardless of the number which were being actived. Flat
              orange is a difficult colour to judge brightness of and radiant
              orange is very difficult to judge in close relative terms.

              Basically what I wanted to say was that the anode reistor is moreof a
              luxury and for added protection. A small reduction in cathode current
              can create a much longer tube lifetime in the right circumstances and
              so I opted to have one, just in case anyone needed to set the
              voltages from a non-adjustable supply which demand odd valued
              resistors.

              As long as the bulk of the current limiting is being done with the
              cathode resistors any anode resistance you need to choose to further
              limit the current for one cathode will not produce a very noticeable
              effect when all cathodes are activated


              Chris
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