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Nixie tube / transistor help — Parallax Forums

Nixie tube / transistor help

bkirkbybkirkby Posts: 6
edited 2009-02-05 21:19 in BASIC Stamp
Can anyone share any sort of advice and/or schematics of how to safely connect a BS2 to a single Nixie tube? I cannot seem to get the transistor to work properly.

I have a BS2, MPS A42 or MPS A92 (not sure which one to use) and a power supply to get my 180v for the IN-8 Nixie tube.

Namely what I cannot figure out is how to close the circuit with the BS2 and transistor. i.e. If I connect the output from the BS2 to the Base of the transistor, where does the ground from the BS2 go?

I am still a huge newbie so please 'speak slowly'.

Thanks in advance
Ben

Comments

  • JonathanJonathan Posts: 1,023
    edited 2009-02-03 00:44
    Use the MPSA42's, they are good to 300V. I don't have am MPSA92 data sheet here, so I don't know the specs. As said above, since the nixies are common anode, connect the collector to the nixie and the emitter to ground. All grounds should be common. You know there are chips that will do this as well, the 74141 being the classic, and there are some modern ones, don't have the part #'s here.

    Jonathan

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • bkirkbybkirkby Posts: 6
    edited 2009-02-03 00:50
    Thanks for the advice. I have some 74141's ordered but they are taking their sweet time to get here... In the meantime, I wanted to do a show-and-tell with one of the Nixies so i am jumping ahead, or sideways...

    As for the ground, do I need a diode in there somewhere to protect the BS2? If so, any suggestions as to which one or where it should go?

    Thanks again!

    Ben
  • Mike GreenMike Green Posts: 23,101
    edited 2009-02-03 01:08
    Don't forget that you need a current limiting resistor in the base lead of the transistor. Something on the order of 1K would give you a base current of 5mA roughly.

    The reverse connected diode you mentioned is for inductive loads like relays, motors, and solenoids. You don't need it in this case.
  • JonathanJonathan Posts: 1,023
    edited 2009-02-03 01:23
    Also don't forget that one carless move with the 180V, and you crater the Stamp. If you have a 74HC595 you can gain another degree of isolation by driving the transistor with it. Be careful ona breadboard, it's easy to have too much fun with the HV. And I speak from painful experience, I got a nice shock and dropped a nixie to it's death! [noparse]:([/noparse]

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-02-03 20:25
    Jonathan said...
    Also don't forget that one carless move with the 180V, and you crater the Stamp.
    You've got to have a car to protect the Stamp?· Would a motorcycle do?

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    · -- Carl, nn5i@arrl.net
  • JonathanJonathan Posts: 1,023
    edited 2009-02-03 23:07
    No, a motorcycle can't sink enough current. You really have to use a car. A RV would be better, but as long as you aren't carless, you should be ok. :0

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-02-04 03:27
    OK, next time I'll use my RV. It's pretty safe, so at any rate we won't end up Carlless.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    · -- Carl, nn5i@arrl.net
  • skylightskylight Posts: 1,915
    edited 2009-02-04 16:48
    Just whatever you do DONT use a Bus!
  • vaclav_salvaclav_sal Posts: 451
    edited 2009-02-05 21:19
    If you feel uncomfortable around anything "taller" than 12V use optocoupler to isolate the BS from your Nixies.
    PS Where did you get the Nixies? E-Bay?
    ·
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