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LCD TV remote control remote control signal is formed mainly by the microprocessor chips, crystal oscillator, amplifying transistor, an infrared light emitting diode and a keyboard matrix composition. It works as follows IC1 microprocessor chip internal oscillator by 2,3 feet composed with an external crystal oscillator X a high frequency oscillator which generates a high-frequency oscillation signal (480kHz). This signal is generated sinusoidal signal and the timing pulse signal fed to 40KHz after the timing signal generator. Sinusoidal signal into the coded modulation as a carrier signal; a timing pulse signal sent to sweep signal generator system, the encoder and the key input command signal encoder is used as the standard time of these circuits.
IC1 internal scan signal generator generates scan pulse signal Fifth different times, from 5 to 9-pin output to the keyboard matrix circuit. When you press a key, the function keys corresponding to the control signal, respectively, from 10 to 14 feet into the key encoder input and output functions corresponding digital signal. It is then output by the encoder means instruction code signal, the modulated signal is modulated on a carrier, is formed with a high frequency pulse train function information, the output pin 17 through the amplification transistor BG promote infrared diode D emits pulse modulated signal.
Now use the remote control frequency of use are 38KHZ, it is a certain way to a different key for encoding, modulation wave generated by a dedicated integrated circuit, emitted by infrared diodes. After decoding a television receiver and then take appropriate action. Infrared pulse signals of different frequencies correspond to different commands, and this pulse is achieved with quartz, quartz vibration frequency after power very quickly and very evenly, so you can use it to achieve different pulse frequency.
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