P228 infrared remote control with production of energy-saving lighting
Posted on Dec 11, 2010 9441
Core device is a circuit pyroelectric infrared sensor BH, when it felt the trace infrared body issued a sensor inside the element will obviously feel that their process of chan
ge relative to the temperature, as a thermoelectric element of self-ferroelectric polarization value is will change in the surface of the element will have run out of charge, and then the gate resistance Rg have the electrical signal change + electric pulse matched internally set by BH FET (FET), you can output a certain amplitude whose pulse frequency is generally between 0.5 ~ 1Hz (which is most sensitive frequency BH), via a capacitor Cl coupled to the preamp tube VTI pre-release. After the pre-amp output signal from its collector, direct coupling to the op amp is Al 3 feet, low-noise, high-gain amplifier, and then by the Al output of 6 feet. A3 composed op amp voltage comparator, RP1 reference voltage divider, when Al is 6 feet output voltage is higher than the reference voltage A3, A3 amplified high-level pulse is output through R6 limiting the transistor VT2 conduction through. V r2 conduction so that the single-shot group consisting of an integrated circuit A4 flip set, A4 3 feet high output, SCR vs opened, lamp H lights up. Transient time one-shot is determined by the R8 and c7, illustrating data about llOs. So if people stop in front of the motion sensor BH, sustainable lighting the lamp; when people leave about llOs, lamp H turns off automatically. Photoresistor RO, transistor VT3 and potentiometer RP2 composition light control circuit, its role is to make the circuit is not in the daytime work. RG in the daytime because the light irradiation resistance was low, VT3 conduction, the saturation voltage is only about 0.3V, so make A4 forced reset terminal 4 feet low, when the group is forced to reset the circuit. 3 output pin is always low, so in the daytime lights are not lit. RO sleepy at night without light irradiation showed a high resistance, VT3 cutoff thereby lifting the blockade on the A4, so the circuit can work properly. RP2 potentiometer used to adjust the light control value illustrates that VT3 under appropriate light turned on or off. Capacitor C2, c5 constitute a low pass filter to eliminate interference pulses. Rt is a positive temperature coefficient thermistor by the sensor BH relatively sensitive to heat in summer due to high temperatures can cause the body heat (constant) temperature (transition and in a significant reduction in the amount of) difference. BH sensitivity decreases. The positive temperature coefficient of resistance characteristics cooked-sensitive resistor is with temperature increases its resistance increases, resulting in the amount of feedback amplifier is reduced, the relative increase of the op amps gain amplification to compensate for the BH sensitivity due to temperature rise and drop off defects. The whole power from the step-down capacitor C11, diode VD2 ~ VD5 bridge rectifier supplied by the post-stage circuit regulator VD1 voltage power supply, sensor front-end circuit that is BH by the three-terminal regulator A2 supply voltage, its purpose It is to prevent the power supply voltage fluctuations may cause malfunction of the circuit in order to improve reliability.