weird tv interruptions

Discussion in 'The Projects Forum' started by Chris15, Jan 24, 2010.

  1. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    hello i was playing with a little relay and the tv in my room and one down the hall started flikering what was happenin and what is this called
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    It could be the sparking that causes the trouble.
    It depends on what is connected to the relays.
    Can you post a schematic?

    Greetinngs,
    Bertus
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Is the relay switching the coax input to the TV?

    If it is you are in the middle of RF theory. There is a reason they use special wire to carry TV signal to TVs. It won't damage the TV unless you do something way out, such as feeding spikes from the coil into the coax line, but you are messing with a carefully constructed RF path by using a simple relay (this sounds worse than it is).

    Unless it is going to cause you problems I wouldn't worry about it.

    BTW, what part of the world are you? It helps because we can make assumptions about the local standards.
     
  4. Chris15

    Thread Starter Active Member

    Apr 15, 2009
    252
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    To bertus, i dont have a scematic as i was jusr playing around, this was a long time ago and i am sure i was trying to connect two relays to latch for a light activated spotlight to come on, and then off with another ldr, i remember that if i connected it in a certain wat the relay would flick in and off wildly, but when it was disturbing tne Tv's i THINK it was humming trying to click, Bill i am in Australia and the coax was not connected in any way, i was just playing with the relay and i noticed the tv it was some sorta wireless disturbence maybe a certain RF signal Chris
     
  5. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
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    It sounds like a basic 'spark transmitter'.

    Each time a relay coil is switched off, it produces a high-voltage spike (which is why snubbers or flywheel diodes are normally added).

    Without any suppression, this high voltage will arc back across the contact switching the coil. Each time this happens a burst of wide band radio noise is produced.

    With the relays buzzing, you would be producing many noise bursts per second - a fair radio jammer!
     
  6. lmartinez

    Active Member

    Mar 8, 2009
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    How did you know that the TV down the hall way was acting up? :cool:
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Because his Mom was watching it, and threatened to kick his keister for messing up the TV while Wheel of Fortune was on.
     
  8. Chris15

    Thread Starter Active Member

    Apr 15, 2009
    252
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    Haha lol yes thats rite SgtWookie, and to Mr Jenkins what you explained how does this work radio jammer? How did it effect the Tv just from a switching relay, how would i recreate this for old times sake? Chris
     
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