The infrared receiving head is introduced

Infrared signal transceiver system of the typical circuit is shown in figure 1, infrared receiving circuit is usually manufacturer integrated in an element, become integrated infrared receiving head. Internal circuit including infrared monitor diode, amplifiers, limiter, bandpass filter, integral circuit, comparator, etc. Infrared diode monitoring to the infrared signal, and then send the signals to and limiting amplifier, the pulse amplitude limiter control in a certain level, regardless of the distance of infrared transmitter and receiver. Ac signal into the band-pass filter, bandpass filter can be achieved by 30 KHZ to 60 KHZ carrier, through demodulation circuit and integral circuit into the comparator, the comparator output high and low level, reducing the launch of the signal waveform. Pay attention to the high and low level of output and transmitter is reverse phase, the purpose of this is in order to improve the sensitivity of receiving. Many different kinds of infrared receiver head, pin definition is also different, generally has three pins, including power supply, grounding and the signal output pin. Depending on the transmitter modulated carrier should choose corresponding demodulation frequency receiving head. Infrared receiver head inside the amplifier gain is very large, it is easy to cause disturbance, therefore in the receiving head VCC (voltage) and the GND PIN feet (ground) PIN feet must be combined with the filter

Capacitance, through expert testing test in 47 uf ceramic capacitor (note: the capacity to 100 uf or 20 uf capacitance will cause the receiving head short distance). Another for VCC (voltage) and Vout PIN feet (output) between string into a 10 k ohms pull-up resistors, pull up effect when the voltage instability. Infrared emitter is available from the remote control manufacturer custom, also can use MCU PWM generation, family control is recommended to use infrared transmitting tube (L5IR4-45) can produce 37.91 KHz PWM, the PWM duty cycle is set to a third, through a simple switch PWM timing interrupt, emission waveforms can be.