how the remote conrol of tv works

Discussion in 'General Electronics Chat' started by spidermanIIII, Jun 26, 2014.

  1. spidermanIIII

    Thread Starter Member

    Nov 22, 2013
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    i want to know how the remote control of tv (transmitter) work and what is its circuit and how does the tv response to it
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Did you try googling it yet? What did you find so far?
     
  3. bertus

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  4. hexreader

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  5. KeepItSimpleStupid

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    Mar 4, 2014
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    A quick explanation is that the remote uses a carrier of typically 38 kHz and some sort of modulation.

    The code used is anybody's guess, but PCM is popular.

    The lenght of the bursts make up the ones and zeros. The lull makes sets things up for the next command.

    So, a simple remote may have a long start bit, so the receiver's automatic gain control can lock on it and then say an n bit word.

    They got smarter in their old age by allowing, a unit number and type of equipment and they have even added some sort of error detection. Some codes might send a code and then the inverted code.

    Some use a different code for repeat.

    They are all different. Check out www.remotecentral.com and also look for RC5 as a type of encoding.

    They are all different.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The first were ultrasonic, you could shake your car keys in front of the set, it would change channels.:p
    Max.
     
  7. KeepItSimpleStupid

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    Yea, wasn't that cool?
     
  8. RichardO

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    A childhood friend had one. The remote control button whacked a metal rod to create ultrasonic vibrations. No battery needed.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    Until the dog ran by, and it's metal chain collar changed the channels and volume. :eek:
     
  10. MaxHeadRoom

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    Right, it was actually a hollow cylinder of the correct diameter that 'rang' at the prescribed frequency.:cool:
    Max.
     
  11. RichardO

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    May 4, 2013
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    Thanks for the correction. It has been a _very_ long time since I saw the remote control -- 1962 maybe. :D
     
  12. AnalogKid

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    The Zenith Space Command.

    Zenith invented the wireless remote (the FlashMatic) with a ray-gun looking thing that had a battery in the handle. Props for pulling it off, but the system had issues.

    For the next gen Space Command, no battery in the transmitter was a drop-dead requirement. The only real failure mode was a fracture in one of the rods that would shift the freq up out of the receiver range. Back then I could hear these things in their normal range, but not when the freq upshifted; it made diagnosis very quick.

    The receiver also used an electro-mechanical device. The input was amplified to drive a thing that looked like a 4-pole relay. Except that the four blades were different lengths, just like the bars in the transmitter only shorter (different metallurgy). One of the four leafs would vibrate depending on the freq driving the coil, and its tip would make contact.

    The sound of the hammer hitting a tuning bar in the transmitter is the reason we call today's remote controls "clickers".

    ak
     
  13. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    So your username is somewhat of a misnomer? :)
     
  14. AnalogKid

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    Young at heart - and a Rush fan.
     
  15. ian field

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    Google for RC5 - its one of the most common protocols.

    Various manufacturers like Panasonic, JVC etc use their own unique code formats.

    It just takes a little rooting around on the web.

    Look in the right places, and there's a lot of detail on the web for people who want to program microcontrollers to emulate the codes.
     
  16. djsfantasi

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  17. ian field

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    Not when a lorry applied its air brakes outside!
     
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