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Automatic Room Light Circuit Schematic Presentation

2014-12-11 12:27  
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The circuit is not a simple circuit. It has a small memory it automatically switch "on" and "off" switch of the light desired fashion. Circuit uses two long-distance love, place one after the other (say half a meter at a distance), so that they can be separated or a feeling of a person entering the room out of the room. The sensor output two long distance relationship, treatment, used in conjunction with a two-color led in such a fashion that when a person enters the room will be able to emit green light, when a person is out of the room it emits red light, and vice versa. These outputs are simultaneously applied to two counters. A counter, will be treated as 1 2 3, etc. When a person enters the room, the other will count as 1, 2, etc. When a person out of the room. These counters use of Johnson decade counter  CD4017  ICs. The second stage consists of two logic circuits can be combined with the output of these two counters and determine whether there are any people who remain in the room or not. Because the circuit LDRs have been used, should be careful to protect them from ambient light. If necessary, you can use ready-made infrared sensor module instead deposit ratio. Sensor is installed in such a way that when a person enters or leaves the room, he intercepted the light falls on them one by one in the order. When a person enters the room, first he would obstruct light falls LDR1, followed by landed LDR2. When a person leaves the room will be the opposite. Under normal circumstances, the light falls on two non-stop long-distance love, so their resistance is low (about 5 kg ohms). Therefore, the pin 2 two timers (IC1 and IC2), which is configured as monostable flip flops, are held near the supply voltage ( 9 v). When sunlight falling on the long-distance love blocked, its resistance becomes very high and pin 2 voltage drops to near ground potential, thereby triggering the flip-flops. Capacitors at pin 2 and the ground has been added to avoid false triggering due to electrical noise. When a person enters the room, LDR1 is triggered, it will lead to the first trigger monostable IC1. Short output pulse immediately charges the capacitor C5, forward biasing transistor pair t1 - t2. But at this moment the collectors of transistors T1 and T2 in a high impedance state, IC2 pin 3 is at a low potential and the diode D4 are non-conductive. But when the same people through LDR2, IC2 monostable is triggered. Its higher pin 3, which may be coupled to the transistor through the diode D4 t1 - t2. Therefore transistors t1 - t2 because capacitor C5 retention fee for some time as its discharge time is determined by resistor R5 (and R7 to some extent). Therefore, some of the leading two-tone green LED lit moments. IC3 same output is also coupled to it as a clock. With the entrance of each person IC3 output (high state) continue to develop. At this stage transistors t3 t4 can not be, because the output pin 3 of IC1 is no longer active as its output pulse duration is very short, the transistor collector is in the high impedance state. When people leave the room, LDR2 followed LDR1 trigger first. Because the bottom half of the portion of the circuit is the same as the upper half, the left part of each of the red color of the instant ignition lead and output in the same manner as progressive IC4 IC3 of the case. The output of IC3 and IC4 (after inversion by the inverter gates N1 through the silicon ceramics) value, and gates (A1 through A4) and lines or (using diodes D5 through D8). The net effect is that when people enter, and at least one output gates are high, resulting in the transistor T5 is conducted and the excitation relay RL1. Bulb connected to the supply via N / O contacts relay RL1 also lights up. When people leave the room until all the people into the room to leave, wired or production continues to remain high, which continues to remain light bulb "in" until all personnel entering the room had already left. Maximum number of people, this circuit can handle is limited to four fifth clock pulse receiving counter is reset. The capacity of the circuit can be easily extended to 9 1 by removing the connecting pin from the reset pin (15) and use of Q1 to your school CD4017 counter output. If this is so, it will require additional inverters, and Gates and diodes.




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