Need help to identify a transformer

Discussion in 'The Projects Forum' started by indy_kid, Apr 28, 2013.

  1. indy_kid

    Thread Starter New Member

    Apr 28, 2013
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    PCB-mounted, 4-pins. The only marking is "TNB" (possibly "TBN") in raised lettering on one tab (see photo).

    Any help getting an ID on it would be greatly appreciated, as I'm stuck at this point and need the specs (I don't have the original, just the image)!

    [​IMG]
     
  2. #12

    Expert

    Nov 30, 2010
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    The only person who could identify that is one who happens to have one or worked in the factory that made this one. The best you can do is measure the turns ratio with a signal generator and an oscilloscope. Then you can guess at the power handling ability by comparing the size to a similar, known transformer, and calculate the probable voltages it was designed for.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    What device is the transformer in? If you need the transformer you obviously have specs or circuit for the device you are building.

    From the image and size, it looks very similar to a lot of 600:600 ohm telecoms transformers I have in my junkbox, used in answering machines and phoneback alarm systems etc.
     
  4. indy_kid

    Thread Starter New Member

    Apr 28, 2013
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    It's in a geiger counter. Mine went dead, and I was able to trace it to the transformer - an open lead or broken winding. The wire is much too fine to try and work with; trying to remove that yellow tape made that pretty clear.
     
  5. #12

    Expert

    Nov 30, 2010
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    If you can post a schematic of the Geiger Counter somebody might be able to derive what the circuit needs.
     
  6. indy_kid

    Thread Starter New Member

    Apr 28, 2013
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    Well, here it is! It's probably not the best, but I was using a freeware schematic program and learning on the fly. The device is very compact, so some components don't physically lie in the positions shown.

    D-15 runs from Pin 8 to Pin 12; no connection with Pin 9 of the IC. D-16 goes from Pin 8 to Pin 11. The other tie points, such as R-12, R-14 and C-33, or R-23 and C-24, are correct. I don't see any other obvious flaws at this time.

    [​IMG]

    The numbering system might seem odd, but I had labeled each item on the board in order. But it's the values that are important, not the name or number of an item!

    Pin #3 on the transformer IS open; the device might be acting as a choke instead of a transformer, depending on the orientation of the coils. That's an idea I got from an 1943 Pop. Mechanics story about building a "B" battery eliminator for tube radios; such batteries could not be obtained because of the war. I might be completely off, but with an open coil, it makes sense to me!

    No rush on this! The company has refused to answer any of my e-mails, so I'll likely end up cannibalizing that GC and use the G-M tube, meter, and other parts in a better-designed unit!

    If anyone can figure it out, PUBLISH YOUR FINDINGS!!! Industrial Test Systems charges $300-400 for their Geiger Counter, and you KNOW that price is jacked up! If a correct schematic is published, they might be more customer-sensitive!
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Just google for a Geiger counter circuit, all they do is generate a high DC voltage until the tube arcs over.

    There are lots of schematics around, with full parts lists etc. :)
     
  8. indy_kid

    Thread Starter New Member

    Apr 28, 2013
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    Yeah, I know that. However, the issue at hand is the broken GC I currently have! I'd rather get that working than build a new one from scratch!
     
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