name this part

Discussion in 'General Electronics Chat' started by ajrenzetti, Oct 14, 2011.

  1. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
    40
    0
    at one point i was going to try to make an induction heater based on this schematic, but i could never figure out exactly what kind of tube was used in it. so, does anyone know the name of the part circled in red in the schematic picture? ive included the image link as well in case you cant see the other picture loaded from file.
     
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
    2,428
    1,328
    It looks like a type of triode to me, but unfortunately I don't know much about tubes :p
     
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    It looks a bit that way, but there is no DC return path from the end that looks like the cathode - just a capacitor. I thought maybe some king of triggered gas tube, if the supply is AC?

    Or perhaps the schematic has simply been copied incorrectly, maybe by someone unfamiliar with standard component symbols.

    Edit: Triode tubes are used in such applications: some of them are really rather big. This one delivers 1.25 Megawatt, with 17.5kW needed just to heat the cathode.

    http://www.thalesgroup.com/Portfolio/Documents/Triode_RS_3700_CJ/?LangType=2057
     
    Last edited: Oct 14, 2011
  4. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    Symbol for a magnetron seems right.
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    The symbol may look like a magnetron, but the circuit shown seems to have external frequency determining parts, and there is no DC path through the device.
     
  6. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    That's exactly what I was thinking.
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    No heater either. Thermionic emission requires a heater.
     
  8. tgotwalt1158

    Member

    Feb 28, 2011
    111
    18
    I think its an old model of triode known as 955 triode. The author seemed to have drawn grid and cathode scantly, may be due to be in hurry.
     
  9. DerStrom8

    Well-Known Member

    Feb 20, 2011
    2,428
    1,328
    I figured it wasn't all there. It looked like a rough sketch to me, but as I said, I don't know much about tubes :D:p
     
  10. K7GUH

    Member

    Jan 28, 2011
    191
    23
    By convention, the heater is often omitted from tube diagrams. I don't understand why one would expect a DC path through the device.
     
  11. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    A DC path through the circuit is required, which is what I was referring to, if this is a vacuum electron tube. Conduction can normally only occur by electrons leaving the heated cathode and moving towards the other electrodes*. In this case however, what looks like the cathode is only connected to a capacitor, so no DC current flow is possible.

    Typically a vacuum tube circuit might decouple the AC voltage at the cathode to common with a capacitor, but there would also be some DC path via a resistor or a choke etc.

    *Edit: Secondary electron emission may occur from other electrodes, but first there must be a path for cathode current.
    Do we assume this may be implied, like the heater connection? In which case, why show the HT input at all?
     
    Last edited: Oct 15, 2011
  12. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
    40
    0
    wow i didnt expect this many posts for the question.

    i cant really tell if this would even work at all. i would have said no a long time ago if the schematic didn't come from a legit corporation for ceramic capacitors. could the tube instead be some kind of vacuum capacitor? maybe an adjustable one?
     
  13. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
    40
    0
    perhaps this could be a vttc induction heater circuit?
     
  14. Lundwall_Paul

    Member

    Oct 18, 2011
    220
    19
Loading...