51 key remote control of new product remote control set top box in 2016
nice ABS + Silicone
Principle of Remote Control Set Top Box
The remote controller is mainly composed of a microprocessor chip, a crystal oscillator, an amplifying transistor, an infrared light emitting diode and a keyboard matrix forming a remote control signal. The working principle is as follows: The internal oscillator of the microprocessor chip IC1 forms a high-frequency oscillator through the 2, 3 pin and the external oscillating crystal X to generate a high-frequency oscillation signal (480 kHz). This signal is sent to the timing signal generator to produce a 40KHz sinusoidal signal and a timing pulse signal. The sinusoidal signal is fed to the code modulator as a carrier signal; the timing pulse signal is supplied to the sweep signal generator, the keyed input encoder and the command encoder as time standard signals for these circuits. The scan signal generator inside IC1 generates scan pulse signals of five different times, and sends them to the keyboard matrix circuit from the output of 5-9. When a certain key is pressed, the control signals corresponding to the function keys are input to the key control encoder from 10 to 14 feet, respectively, and the digital signals of the corresponding functions are output. Then, the instruction code signal is output by the fingerprint encoder, modulated by the modulator on the carrier signal to form a high frequency pulse train containing the function information, and the output of the 17 pin is amplified by the transistor BG, and the infrared light emitting diode D is pushed to emit the pulse modulation signal.