Nixie clock schematic

Discussion in 'The Projects Forum' started by magnet18, Jan 25, 2011.

  1. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Hi everyone,
    I recently finished the schematic for my nixie clock, and i was wondering if it would be too much to ask for someone to look over it and make sure there are no giant flaws or anything, i looked over it myself but i wanted to be sure before i started making a schematic

    Any help or advice would be greatly appreciated, thanks :)
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    That last schematic, where you connect the two outputs of the 4060 together. That bothers me a lot. It is a good way to zap the chip, as if one output is high and the other low the 4060 could just kick up its heels and die.

    Better to have a resistor on pin 2 of U2 as a pull down (something large), and a toggle switch connecting one or the other (but not both).
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    On the CD4060 pin 3 (Q14), use a 10k resistor in series between that pin and the switch. That way when the switch closes, the input from pin 3 (Q14) is overpowered by the signal from pin 14 (Q8) and it is well within the specifications of 4000 series CMOS to do that.
     
  4. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Thankyou both, ill fix that, come to think of it it might have caused a problem earlier that i couldnt identify... :)
    Bill, i was wondering if expressPCB has an auto-place/auto-route feature, i thought it would but i dont see one

    Thanks again, i realize looking through schematics can be time consuming and boring, especially when its spread over 4 pages :p
     
  5. SgtWookie

    Expert

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    You don't have any resistors on the bases of your transistors. Your 4017's won't like that very much, as the transistor bases will look like forward-biased diodes and keep the 4017 outputs from rising above about 0.8v. That will be very hard on them.
     
  6. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Wow, i cant believe i actually missed that, especially since theyve been in every other schematic ive drawn and every prototyme ive made... :/
    thankyou for pointing that out

    also, would putting 2 diodes on pins 3&14 of the 4060 work to protect it?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Well, it would - but then you would need another 10k resistor as a pull-up or pull-down, depending on which way you installed the diodes.

    It would be a lot easier (and more reliable) to simply use a single 10k resistor in series from pin 3 like I said before. One inexpensive and reliable part resolves the problem completely.
     
  8. tom66

    Senior Member

    May 9, 2009
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    You also appear to have 12Vac coming into a transformer and producing 170V; this is fine, but you need to rectify (preferably full-wave) the AC and filter it out. Depending on the logic draw, you may need a large filter cap. Also, a bettery battery backup system would be a relay which is energised when AC is plugged in but deenergises when AC is removed. Also, don't nixies require DC 170V, not AC? If you're using AC you won't be able to use the transistors.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    He is using a DC-DC converter module that works with an input of ~11v-18v and outputs 180v at low current.

    I didn't realize before that he was using just one current limiting resistor. I would use one per Nixie tube. The optimal value hasn't been determined as of yet; he hasn't posted what the current is right now - and it would be difficult to measure when there are six Nixies in parallel and just one resistor.
     
  10. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    alrighty, i edited the schematics (not added 33K resistors yet, will soon), is this what you meant with the 10K?
     
    Last edited: Jan 26, 2011
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Yes, you put the 10k resistor in the correct place for the 4060.

    In the 2nd schematic, Q15's emitter does not have a ground.
    "Minuets" are a type of dance music in 3/4 time, originating in France in the 1700's. It should be "minutes". ;)
    Bach's Minuet in G: http://www.youtube.com/watch?v=V4mgYbWC-HY&feature=related
     
  12. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    nice catch, thanks :)
    and have i really been misspelling that all my life?!?!?!
    i feel funny inside now... :(
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Don't feel too bad - my wife has a Masters' degree, and she asks me how to spell words all the time. My Grandmother graduated from college with a degree in English. She could be quite unpleasant if I made grammatical errors or misspelled words. :( I'm just giving you a "heads' up" on how it's spelled. :)
     
  14. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Yea, its just a funny feeling, Ive been spelling minuets like that for as long as I can remember (albeit that's not really that long), and this is the first time anyone has ever pointed it out.
    I'm not sure whether to bust out laughing, search my computer for every instance of the word, or make the conscious decision to keep spelling it like that forever and see how many people notice :)

    In any case, English just isn't my thing, Ive come to terms with the fact that my brain's wired for electronics (pardon the pun :) ), science and engineering.
     
  15. Wendy

    Moderator

    Mar 24, 2008
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    Firefox has a real time speel checker. Wurks for me.
     
  16. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    So does Google chrome, i guess it just doesn't catch minuets since its an actual word...
    I'm in the process of editing the schematic again, they should be up in a few minuets.
     
  17. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Heres the schematics, updated and corrected for hopefully the last time :)

    I'm also kinda wondering if theres anything with them that isn't wrong, but is just not a good habit to get into or looks sloppy, this is the first time Ive done a schematic on the computer and I don't know if it looks "unprofessional".
     
  18. SgtWookie

    Expert

    Jul 17, 2007
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    It's pretty good so far.
    You have a label hanging outside the border in one of them.
    I'd change the "logic" label to Vdd, as that's what it is.
    You could keep the HV part of it as 170v, or change it to B+, which is what the old standard was for tube/valve plate voltage in the States.
     
  19. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Yea, the label for the decimals on the tubes wasn't positioned correctly, and for some reason it wont let me move it...
    Thanks for the tips and for looking over it :) i guess since the bugs are all out I should start on a board layout, if I only wasn't so busy with school :p
    is it at all possible to do toner transfer with an inkjet printer if I have the right material?
    Ive seen sites that say it is and sites that say it isn't, id like an opinion before I risk messing up my printer.
     
    Last edited: Jan 28, 2011
  20. Wendy

    Moderator

    Mar 24, 2008
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    Your DC to DC convertor is a black box, not a transformer. Not a big deal, but it counts.
     
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