How does a TV tune its frequency?

Discussion in 'General Electronics Chat' started by davidGG, Nov 27, 2013.

  1. davidGG

    Thread Starter Member

    Dec 22, 2012
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    I've experimented with radios and the only way to change the frequency is by tuning the tank circuit which is either by varying the capacitor or inductor.

    How does a TV do this when I change the channel with a remote? Is there some sort of rotating part in the TV?
     
  2. Metalmann

    Active Member

    Dec 8, 2012
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    223
    Not anymore.....nowadays, it's all digital tuning.
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    The frequency generation part of the local oscillator is tuned using phase-locked loop and frequency division.

    The tank circuit is tuned using varactor diodes.
     
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  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,997
    745
    They used a Varicap diode for tuning, the diode varies its Capacitance as the Voltage applied to it varies, see circuit

    Modern digital TVs use I2C bus methods SCL and SDA.

    Old analogue tuners used a sweeping voltage of 10 to 28v and used a precision zener of 33v as the reference supply,

    see old tuner

    manual tuning
     
    Last edited: Nov 28, 2013
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  5. davidGG

    Thread Starter Member

    Dec 22, 2012
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    Do car radio tuners work the same way or is the tuner knob a variable capacitor or inductor?
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    Most modern radios use digital frequency selection. They no longer use variable capacitors nor variable inductors.
     
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