当发现黑暗时,就像将手放在传感器上时,这里描述的电路会停止音乐声。该电路可用作早晨警报。将其安装在窗户上,因此,当灯光掉落时,它将开始给您旋转的声音以醒来。晚上,您可以使用它关闭楼梯的光线。
当您关闭房间的光线时,几乎没有修改,就像您可以在输出时(代替扬声器)连接继电器以关闭灯泡。该电路可以使用铅笔单元进行操作,因为它的操作仅需少3V。由于电路中使用的组件数量很小,因此很容易安装它。lDR是一种设备,其灵敏度取决于落在其上方的光强度。
Thedark sensor circuitdescribed here stops the musical sound when darkness is detected like when you put your hand above the sensor. This circuit can be used as morning alarm. Install it on your window so when the light falls on it will start giving you melodious sound to wake up. In night you can use it to switch off the light of staircase. When you switch off the light of your room with little modification like you can connect relay at output (in place of speaker) to off the bulb. This circuit can be operated with pencil cell as it require less only 3V for its operation. It can easily be mounted because of number of components used in circuit are quite small.
Description
Thisdark sensor circuitexplains the principle of operation ofLDR(light dependence resistor). LDR is a device whose sensitivity depends upon the intensity of light falling on it. The resistance of LDR decreases when intensity of light falling on it increases and vice versa (resistance increases when intensity of light falling on it decreases). In dark or in absence of light, LDR exhibits a resistance in the range of mega ohms which decreases to few hundred ohms in presence of bright light.
This phenomenon can be measure with the help of multi-meter. For measuring keep your multi-meter in ohm or resistor measurement region. When you cover the LDR its resistance will be very high and when you place it in light it decreases. We are utilizing this property of LDR to act as a sensor, since a varying voltage drop can be obtained with varying light. In this circuit amount of light is vary because of the shadow of the visitor falls on LDR. So care should be taken while mounting the LDR.
When continuous light fall on LDR its resistance is very low hence it will allow supply at pin 2 of IC1 and we get output pin 1.These weak signals then amplify by transistor and feed to speaker attached to it and we hear a melodious sound. But in darkness resistance of LDR is very high and it does not allow IC1 to conduct, therefore transistor connected at output is in cut off mode and speaker will not sound. We have connected a zener diode at pin 2 of IC1 because excess voltage more than 3.3V will harm the UM66 IC. The circuit described here is more of a sensor application with a speaker attached to it as output. However, depending upon the application, user can attach a night lamp or series of small LEDs to the circuit with the help of relay. You can also use different IC like UM3561, UM3562 etc in place UM66 if you want different sounds for this refer to datasheet of UM3561.
Fig. 1: Image Showing a Simple LDR Dark Sensor Circuit
Circuit Diagrams
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