How a remote control works different things?.

Discussion in 'General Electronics Chat' started by Whatashame, Mar 22, 2016.

  1. Whatashame

    Thread Starter Member

    Nov 30, 2015
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    A remote control operates several things, say volume, channels n so fourth. What is it doing that this can be done using only one receiver and transmitter? Is it changing the resistor or cap... to the trigger of the microchip it's using.? What is going on? Help anyone. If this has been asked n answered, please direct me to that post please.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    It sends different digital codes depending on the function. Many remotes share carrier frequencies, but the codes sent over that carrier vary by manufacturer and function.
     
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  3. SLK001

    Well-Known Member

    Nov 29, 2011
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    Remote controls use coding for the different functions. Say channel up is 1010011, channel down is 1010010, volume up is 1011000, volume down is 1011001, etc. A MPU handles all the changes - the remote only tells the processor what to do.
     
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  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    If you could see infrared light and looked at the emitter on the remote, you would see that it appears to flash rapidly. Each flash actually is a burst of flashes much too rapid to see individually. This rapid flashing can be thought of as a modern version of Morse code. This coding sends numbers to the receiver based on the function (volume up, channel down, etc.) and the manufacturer.

    http://electronics.howstuffworks.com/remote-control2.htm

    ak
     
  5. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    Some smarphone's cameras (such as mine, a Samsung A3) have the ability to "see" in the infrared. If I turn its camera on, and point the tv remote at it, I can watch it flash in the smartphone's screen. It's really cool.
     
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  6. AnalogKid

    Distinguished Member

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    Yeah, just about any CMOS or CCD sensor works for that.

    ak
     
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  7. Papabravo

    Expert

    Feb 24, 2006
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    Here is an article on the NEC protocol that was used in the Wadia audio products line.

    http://www.sbprojects.com/knowledge/ir/nec.php

    NEC used to make dedicated IC's for this protocol, but now any micro can encode and decode this stuff more efficiently and flexibly than a dedicated IC. Every command takes the same amount of time because there is the data and it's complement in each 4 byte frame.
     
    Last edited: Mar 23, 2016
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  8. InspectorGadget

    Active Member

    Nov 5, 2010
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    Yes but CMOS/CCD cameras typically have IR cut filters because they're very sensitive in the IR range but the IR focuses at a significantly different point and results in severe chromatic aberrations.

    I notice my camera phone, my Canon 14MP camera, and my Panasonic surveillance camera all display the IR emission of a remote control, but not too brightly. I bet they use a mild cut filter and maybe have improved lenses to reduce the aberrations.

    I recall recently running across a camera that did not show the IR at all. Might have been one of my old imagers. Back in the early days of CCD's in Machine Vision applications, the cut filters were severe and we had to manually remove them if we wanted to see in the IR.
     
  9. Whatashame

    Thread Starter Member

    Nov 30, 2015
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    To add to my question, I have a small transmitter and receiver pcbs. 1 with 3 pins, Vcc, GND and like an output. The transmitter has 4 pins and can work on a little higher voltage then receiver, which is 5 V and other is 3 volts. The 4 pins are marked, I beleive, Vcc, GND, and 2 are D , or Ds, I can't remember right now. When you connect D to Vcc , it lights up a LED on the receiver showing it's working. The frequency it uses is, 433.4 Hz I beleive. You can operate 1 thing with this evidently. People like these inexpensive devices to operate their projects, say a small relay. To get this transmitter to operate say 3 things, what would have to change? It does have a trimmer on the pcb with wax over it so you don't touch it . I'm only asking a general question here just to continue what was explained to me. Thank you! thank you very much thank you very much for your answers. Your answers were very helpful and interesting. Now I'm asking about the electronic part. What is going on?
     
  10. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Your question has already been answered, you need a means to encode and decode key press information. This can be done in software or with a dedicated chip like the Holtek HT12:

    [​IMG]
     
    Last edited: Mar 24, 2016
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  11. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The 433.4 Hz number is suspicious. Can you post photos of the transmitter and receiver? A link to where you bought them? part number?

    ak
     
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  12. gerty

    AAC Fanatic!

    Aug 30, 2007
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  13. MrChips

    Moderator

    Oct 2, 2009
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    Just a simple case of a missing M.

    Like 433.92MHz.
     
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  14. InspectorGadget

    Active Member

    Nov 5, 2010
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  15. ian field

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    Oct 27, 2012
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    One of the most popular RC protocols is RC5 - there's loads of pages about it on the web, some of the pages discuss RC in general. so a bit of browsing will find the names of other types.
     
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  16. bertus

    Administrator

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  17. Whatashame

    Thread Starter Member

    Nov 30, 2015
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    Here is correct information and photos of the
    I now have photos and correct MHz and other information. Now I have to learn or figure out how to post them so you can see them. Did not know this can be done on this site. That would make it so much easier for all you good people helping me learn.
     
  18. Whatashame

    Thread Starter Member

    Nov 30, 2015
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    Screenshot_2016-03-24-18-01-18.png
     
  19. Whatashame

    Thread Starter Member

    Nov 30, 2015
    83
    12
  20. Whatashame

    Thread Starter Member

    Nov 30, 2015
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    Wow, I did it. This is so simple now. New simple question. Can I operate more then one thing using this device? No is my answer. What do you or any one else think? Have you used this same device yourself and if so, what are you using it for?
     
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