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Beginners question re attenuation

Discussion in 'Hobby Electronics' started by Robert Murphy, Jan 14, 2004.

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  1. Hi all

    I have an old mono TV, which doesn't have any sort of AV inputs or outputs.
    It does have a front mounted speaker which seems reasonably accessable. I'd
    like to have an output for both headphones and /or a line level out for the
    amp, into which I could plug some headphones.

    Is a simple resistor divider OK for this, taking the output to the speaker
    and using a switched phono jack that I could mount into the case somehow?

    Thanks
    Rob
     
  2. Rod Speed

    Rod Speed Guest

    One thing to watch out for is that those older TVs often have
    a hot chassis with full 240V on it and that will end up on the
    addon speaker output jack if you dont allow for that.
    Attenuation wise, yes. Just watch out for a hot chassis tho.
     
  3. Phil Allison

    Phil Allison Guest



    ** When there is no AV connections and NO earphone jack then the odds are
    very high the TV is one with a "hot" chassis. You cannot safely make *any*
    audio connections to the circuit of such a TV set.

    If you post the make and model of the set someone here may know for sure.




    ............. Phil
     
  4. Thanks for the replies. I'm glad I looked before I leaped in here.

    It's an NEC CT-2003MH, seems to be some sort of international model with
    PAL/NTSC/SECAM.

    Even if I don't 'touch' the chassis, and just use the two speaker terminals,
    I guess one of those is going to be at, ahem, ground potential, is that
    right?
     
  5. Phil Allison

    Phil Allison Guest


    ** No way - both speaker wires will be at high potential.

    Otherwise there would be a kinda loud hum don't you think ?




    .............. Phil
     
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