Infrared Plastic Remote Control For PS Audio / Schiit Audio / For TOYOTA Vehicle With 16 Keys
Small remote control is very fit for our client , most of the client select this model for the audio and amplifier product . we have supplied this model to TOYOTA vehicle . The encoder and carrier generator in the Cmos4-2 input "and not" gate CD4011 are not referenced here, because CD4011 is used as an analog signal when it oscillates to generate square wave signals.In order to ensure the reliable starting voltage of the circuit, its working voltage needs more than 4.5V, and the minimum working voltage of 74HC00 CMOS integrated circuit is 2V, so the use of 3V power supply, can work reliably.2. The remote receiving demodulation circuit figure 3 is the infrared receiving demodulation control circuit, and IC2 in Figure 4 is LM567.The LM567 is a phase locked loop integrated circuit. It is installed with 8-pin, double-row, plastic plug. The working voltage is +4.75?+9V, operating frequency from DC to 500kHz, static current around 8mA.Today foot for the output end, static for the high level, is composed of the internal collector open transistor, allowing the maximum perfusion current of 100mA.In view of the complexity of the internal circuit of LM567, only the basic functions of the circuit are described here.
Resistor (R3+RP) and capacitor C4 of LM567 determine the central frequency of the internal vCO: F01, F01 =1/1.1RC. And capacitors C3 and C4 are connected to the ground to form a filtering network, among which capacitor C2 determines the capture bandwidth of the phase-locked loop. The larger the capacitance value, the narrower the loop bandwidth.(1) The capacitor C3 connected by the foot is more than 2 times of the foot.After making clear the basic composition of LM567, the working process of the circuit in FIG. 4 is analyzed.IC1 is infrared receiving head, it receives the infrared signal from the figure 1, received still is 38 KHZ carrier frequency, modulation signals after IC1 demodulation, on its output side OUT output frequency square wave signals for f1 (see figure 2), as long as the center frequency of LM567: f01 transferred to (RP) with the launch of f1 (see figure 2), namely f01 = f1, is when the transmitter launch LM567 began to work, end feet from high level to low level, the low level make triode conduction, 8550 in point A switch signal output drive D trigger latch,It then drives various switching circuits to work.In this way, as long as you press the micro switch K in the circuit shown in Figure 1, namely transmitting infrared ray and receiving circuit Figure 4, you can output the switch signal to open the control circuit, and then press the switch K to close the control switch signal, which completes the complete control function.3. The frequency on multi-channel controller using circuit of figure 1 and figure 4, you can realize multi-channel remote control, namely, in the IC1 consisting of low frequency oscillator, its circuit model remains the same, only change the resistor R2, can form some kind of R multiple frequency - rate of different low frequency oscillator (coding), using the micro switch switching, 38 KHZ carrier circuit share;In the receiving circuit, the integrated infrared receiving head is shared, and the LM567 phase lock and the rear phase lock drive control circuit are set with the same number of encoders at the receiving end. The oscillation frequency of each PLL corresponds to the frequency of the low-frequency coded signals of each encoder.In this way, when the transmitter (Figure 1) presses different buttons and the carrier signal is connected to the modulated signal of different frequency coding, the level of each corresponding LM567 will change at the receiving end (Figure 4), thus forming the multi-channel control signal.The working mode mentioned above is called the coding mode of frequency rating system.The advantage of this kind of frequency division system is that it can realize multi-channel control, but the disadvantage is that the circuit is complex, for the control circuit with few ways, because the circuit working principle is simple, it is still useful to the general electronic technician