Power amplifier remote control, projection power amplifier remote control, 5.1 power amplifier remote control, power amplifier wireless remote control

Power amplifier remote control, projection power amplifier remote control, 5.1 power amplifier remote control, power amplifier wireless remote control

TV remote control

TV remote control is a device for remote control of equipment. Modern TV remote control is mainly composed of integrated circuit chips and buttons, which are used to generate different information.

There is a CPU called central processing unit (CPU) in English. It is the computer of the TV. During the manufacturing process, the CPU inputs various TV menu password information. As long as the TV remote control signal transmitter sends the corresponding password, the TV remote control can be realized.

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The microprocessor chip is composed of Chinese TV remote control type TV remote control, and the crystal resonator frequency is 38KHZ

The TV remote controller is mainly composed of microprocessor chip, crystal resonator, amplification transistor, infrared light emitting diode and computer keyboard drainage matrix. The working principle of the microprocessor chip is as follows: the internal crystal oscillator of the IC forms a high-frequency crystal oscillator through the 21. tripod and the external oscillating crystal X to generate a high-frequency oscillation signal (480kHz). After the signal is sent to the timing signal generator, 400KHz square wave signal and timing input pulse are generated. The square wave signal is sent to the encoder as a carrier signal; The timing input pulse is sent to the scanning signal generator, and the key control input encoder and instruction encoder are used as the time standard signals of these circuits.

The scanning input pulse of different time in IC5 is output to the computer keyboard drainage matrix circuit from 5 to 9 pins. When a button is pressed, the control signal corresponding to the function button is input from 10 to 14 feet, and the corresponding function digital signal is output. Then, the code encoder outputs the command code signal on the carrier signal through the modem to form a high-frequency pulse string containing functional information, and outputs a 17-foot BG through the transistor to drive the infrared light emitting diode D to send a pulse width modulation signal.

working principle

The TV remote control uses a frequency of 38KHZ. It encodes different buttons in some way, generates modulation waves through special integrated circuit chips, and transmits them through infrared diodes. After receiving the TV, decode it and then perform the corresponding actions. The infrared input pulse of different signal frequencies corresponds to different commands and is realized by quartz crystal. After electrification, the vibration frequency of quartz crystal is very fast and uniform, so different pulse frequencies can be achieved.

Infrared remote control system

The universal infrared remote control system is composed of two parts: transmitting and receiving, and is controlled and operated by the special integrated circuit chip for encoding/decoding. The transmission part includes computer keyboard drainage matrix, coding and modulation, and LED infrared transmission includes optical and electrical conversion amplifier, demodulation and decoding circuit.

TV remote control signal transmitter and its coding

The signal transmitter of TV remote control has many special chips, which can be divided into two types according to the coding method. Here, we explain a chip that is widely used and easy to decode. Now the uPD6121G of NEC in Japan takes the composition of the transmission circuit as an example to illustrate the coding principle. When the key of the signal transmitter is pressed, the TV remote control code will be sent, and the key pressed will be different from the TV remote control code. The TV remote control code has the following characteristics:

The pulse width is 0.565ms, the interval is 0.56ms, and the cycle time is 1.125ms, which means binary "0"; Binary "1" is represented by a combination of pulse width of 0.565ms, interval of 1.685ms and cycle time of 2.25ms.

The above "0" and "1" 32-bit binary codes consist of 38 kHz. In order to improve transmission efficiency and reduce power consumption, secondary modulation is carried out. Then, infrared radiation is generated through the infrared emission diode and emitted into space.

After pressing the button, the TV remote control will send the same 32-bit binary code periodically, with a cycle time of about 108ms. The delay time of a group of code itself and the binary contain "0" and "1" between about 45 and 63 ms.

When a key is pressed for more than 36ms, the crystal oscillator activates the chip and transmits a set of 108ms coded pulses. The 1088ms start code transmits the code (9) ms), the conclusion code (4). 5ms), the low 8-bit address code (9) ms~18ms), the high 8-bit address code (9) ms~18ms), the 8-bit data code (9 ms~18ms) and the reverse code of the 8-bit data code (ms~18ms). If the key is pressed for more than 108ms and still not released, the next transmitted code (serial code) will only consist of the start code (9ms) and the end code (2.5ms).

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Code format (the receiving code shall prevail, and the receiving code is opposite to the transmitting code)

① Bit definition

② Single-issue code format

③ Format of serial code

Receiver and decoding

The integrated infrared receiver is a kind of infrared reception from infrared reception to output and amplification. It does not need any external component TTL to work with all levels compatible with the level signal. It is applicable to all kinds of infrared remote control and infrared data transmission.

Failure handling

1. Turn on the photo function of the mobile phone, aim the TV remote control at the camera, press the TV remote control, and see if there are white spots on the screen.

2. Find a semiconductor radio, adjust the frequency to about 455-650KHZ (preferably the frequency position without a radio station), aim the TV remote control within 3 meters near the radio 0, press any key, and the radio will emit "da" sound; When you press the key repeatedly, you can hear "da", "da", "da" sounds, which means that the TV remote control oscillates and the computer keyboard circuit is normal, but it does not indicate the quality of the infrared emission tube. If there is no such phenomenon when pressing the button, it means that the TV remote control must not work properly.