CRT 3400V pin - what is current - roughly?

Discussion in 'The Projects Forum' started by slackguy, Feb 13, 2016.

  1. slackguy

    Thread Starter Member

    Feb 11, 2016
    29
    1
    hi. i have a diagram showing pinout and voltage (thousands of volts) for the high voltage pin. nothing i can find shows me the current draw requirements. i know it's stepped up (35v or 200v) to 3400v by a small doorbell size xfrm and some quite ordinary (but large) film capacitors, and some circuitry to allow it to be adjusted by an intensity knob.

    i wish to buy a new xfrm but unsure what rating i need.

    anyone have any clue about current draw of the HV pin for CRT (mind you - this crt doesnt use a flyback with a cup at the tip at 25kV, it has a plate far closer to the heater that needs only 3.4kV). know anyone you can ask?

    an amp? milliamp? should it be DC or pulsed? i just have no clue.
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    Last edited: Feb 13, 2016
  3. slackguy

    Thread Starter Member

    Feb 11, 2016
    29
    1
    thank you very much!

    i later googled an old article showing old radio reciever tubes of 500mA accelerator plate. i was (still may) about to just hook the 6.3V up for a hot plate, find a HV source (around 2k is all i have on-hand to build with) to see if a spot appears. otherwise i must order parts and have some hint of what parts to order (a high current high voltage xfrm would be way bigger and more expensive than a low current hv i'm sure you know - two different ball-parks)

    i may convert it to LCD. it may be that "drivinga tube" really should be put in the past. lower power, lighter, accurate - color-able. my intention was not a (weeks) long project to revive a limited life tube (which is working like new though - so i though why not use it?). my intent was to simply to purchase a replace a part for a reasonable fee (not an antique restoration / aviation fee) :)
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
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    hi,
    Take great care that you do not burn a black spot on the CRT's phosphor, [ its easily done!!] also check the Ion trap magnet is correctly positioned.

    For a CRT of say 12/15 inch dia or so, you need approx 15K to 25K.

    E
     
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