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Cathode Ray Tubes

  1. Apr 12, 2007 #1
    Is there anybody out there that can help me??

    Ok in a TV set, the electrons that are emitted come from the heating filament. Now as i read on this site...the heating filament replenishes its stock of electrons from an AC supply. I understand that bit. So there is an AC supply of electrons to the heating filament.

    now comes the cathode and anode that have a potential difference across them. where do they get their potential difference from? Is there a separate circuit? Because they need a very large potential difference and as i read somewhere previously, the heating filament only needs about 6.3V. So i don't understand how if i had to draw a circuit diagram, i would do it. Then to confuse me more, we only plug in one adapter when plugging in a tv. So the current from this adapter, is it split??

    I get the basic stuff of how the electrons are emitted, then accelerated, then their kinetic energy carries them past the anodes to the surface. But its just the earlier part as to how the circuit itself operates. Id really appreciate if someone could help me out on this....my email is aku2590@hotmail.com if ud like to write to that....
    Thanx alot...
  2. jcsd
  3. Apr 12, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Yes, there is a high voltage power supply which provides the accelerating potential. Not sure what the moderen tubes run at but historically were somewhere around 15kV, possibly as high as 25kV.
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