CRT monitor radiation measurement project

Discussion in 'General Electronics Chat' started by regulaz, Jan 4, 2013.

  1. regulaz

    Thread Starter New Member

    Jan 4, 2013
    hi im new here so hello fellas!

    i'm using an old school 21 inch CRt monitor as those used in graphics industry around 6 years ago.

    i was curious about how much radiation it was actually outputting.

    there is an anti radiation screen in front of this with a grounding cord which goes into the ground of the electrical outlet.

    i took a multimeter set it on AC 2 volts setting and it measured 300 millivolts.

    now im curious if this is actually the electric radiation being measured or is this something else?

    does this prove the anti radiation screen is necessary for CRT type monitor?


    one more question my 29 inch CRT TV has a 2 pronged plug and measured in the same way as above shows 40 volts... the cable box when turned on increases this 40 volts figure to around 100-200 volts fluctuating. when i touch the base of the cable box with one lead and the ground with another lead it read 90 volts.

    it looks a little dangerous to me, but im not sure if im measuring the radiation or something else. i have 220 volts 50 hz power system here.

  2. bertus


    Apr 5, 2008

    There will be two kinds of radiation in CRT monitors.
    There is the magnetic radiation, due to the deflection circuit.
    Most of it will be reduced by a metal shielding inside the monitor.
    The other will be static electric radiation, due to the high voltage needed for the CRT.

  3. regulaz

    Thread Starter New Member

    Jan 4, 2013

    Thanks Bertus. What about elf/vlf field radiation?
  4. regulaz

    Thread Starter New Member

    Jan 4, 2013
  5. regulaz

    Thread Starter New Member

    Jan 4, 2013
    can someone tell me what is this 300 millivac figure about? is it the radiation screen doing its job or is this some spurious radiation?
  6. P-MONKE


    Mar 14, 2012
    I wouldn't worry - look up HERP HERO and HERF on the 'net. ;)
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    300 mVolts is a normal reading on an AC volt meter when the leads are not in contact with each other. Standard reception from the 60Hz mains and other signals in free air. The number will bounce around from 0 to 500 mVolt in my area (a few seconds low, a few seconds higher).

    That 300 mVolts just might be when I am near the meter. I did sit too close to our old TV when I was a kid and the effect may still be lingering.