LED transmitter

The infrared receiving diode generally has two kinds of circular and square.

Due to the infrared LED transmitter power is generally small ( about 15mW), so the infrared receiving diode receives the signal is very weak, so we should increase the high gain amplifier circuit.

A few years ago used PC1373H, CX20106A and infrared receiving special amplification circuit. In recent years, whether amateur production or formal products, mostly uses the finished infrared receiving head.

The finished product by the infrared receiving head package roughly two ways: using a metal shield; a plastic package. Both three pin, whereby the power supply is (VDD ), the power of negative (GND ) and data output ( VO or OUT ). The infrared receiving head pin arrangement for different models and different, can refer to the manufacturer’s instructions. The finished product by the infrared receiving head has the advantages of no need of complex debugging and shielding shell, is used as a three transistor, a very convenient.dvb t tuners
But the attention in the use of the finished product by the infrared receiving head carrier frequency.

Infrared remote control of the carrier frequency is 38kHz, which is composed of a transmitting terminal used by the 455kHz Tao Zhenlai decision.

At the transmitting end to the oscillator for integer frequency divider, frequency dividing coefficients generally take 12 / 12 = 37.9, 455kHz kHz = 38kHz. There are also some remote control system using 36kHz, 40kHz, 56kHz, generally by the transmitting end of crystal oscillation frequency to decide.

Infrared remote control feature does not affect the surrounding environment, do not interfere with other electrical equipment. Due to its inability to penetrate walls, so different rooms can use a common household remote controller without mutual interference; circuit debugging is simple, as long as the given circuit connection without error, without debugging can be put to work; codec easily, can carry out remote control.

Due to various manufacturers to produce large quantities of infrared remote control integrated circuits, need how to. Therefore,dvb t receivers
now the infrared remote control in household appliances, indoor distance ( less than 10 meters ) remote control has been widely used.

The multiplexer is controlled by the infrared remote control system to control the infrared transmitting portion generally has many keys, representing the different control functions. When the transmitting terminal press a key, corresponding ground at the receiving end has a different output state.

The receiving end of the output state can be divided into pulse, level, self-locking, interlocking, the five forms of data. ” Pulse” output is when the transmitter button, the receiving end corresponding to the output of an “effective pulse width”, generally about 100ms. ” Level” output refers to the transmitting terminal press key, the receiving end of the corresponding output” effective level”, transmitter release button, the receiving end of” effective level”.

Here the” pulse” and” effective level”, may be high, or they may be low, depending on the corresponding static state output pins, such as static as low,” high” effective; such as static as high,” low” effective. Most cases of” high” effective. “Locking” output refers to the transmitting end each time you press a key,cable supplier the receiving end of the corresponding output ends of a state change, namely the original for the high level to low level, the original low level to high level.

The output suitable for use as a power switch, a mute control. Sometimes called the output form is” reversed phase”. ” Interlocking” output refers to multiple output are clear, at the same time only one output effective. Television channel selection is such a situation, such as light, speed control, audio input selection.

” Data” refers to the number of output emissive key number, the receiving end of the output to form a binary number, to represent different key input.

In general, the receiving end except for a few bits of data output, there should be a” data output, so as to effectively” after class to fetch data. The output form is generally used with single chip processor or microcomputer interface. In addition to the above output form, and” latch” and” temporary” two forms. The so-called” latch” output refers to the transmitting end every time the signal receiving end, corresponding to the output to be” stored”, until it receives a new signal so far;” temporary” output and the output of similar” level”.

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