Many of us have modular kitchen which have chimney to extract smoke out so that smell of smoke will not fill in kitchen and avoids the harmful effects of smoke on furniture and kitchen utensils. But sometimes it happens we forget to switch on the chimney which results in smoke in kitchen and sometimes we forget to off the chimney leading to the wastage of electricity and money. So to solve this problem we have described a circuit which will switch on the fan automatically when smoke reaches to point and off the fan automatically.You can also use this circuit while soldering because as we know solder fumes are not good for health so it will on the fan to extract the smoke present in room leaving smoke free area.

这是一个简单的射击游戏，包括红外脉冲发射器和接收器。有8个白色LED和1个绿色LED会定期点亮。当绿色LED亮起时，玩家必须向接收器射击。这是一个简单的初学者项目，可用于制作更复杂的项目，例如“激光标签游戏”。该电子游戏的红外枪（发射器）是围绕IC1计时器（NE555）建立的，该枪支是一个可确定的多构师，中心频率约为35 kHz。接收器电路具有3个主要ICS - 2个NE555S（一个作为不可分割的多振动器连接，另一个用于单个可单位操作）和1个CD4017B（十年计数器）。这些电路可以修改以制作“激光标签游戏”。阅读更多信息，以了解该电路中如何使用IC555及其工作原理。

此处介绍的电路为固定计时器间隔操作。因此，与继电器连接的设备或机器同时运行。设备打开后，当继电器关闭时，将在固定（设置）时间间隔后自动关闭。时间间隔可以变化，并在7个段显示中显示。这种电路可用于许多应用程序以在固定时间间隔内操作任何设备或机器。

The 8-LED Flasher is built around Timer and Counter ICs. It Flashes 8 LEDs sequentially and the flashing speed can be controlled by a potentiometer. This can be used as a design pattern for decoration. But theoretically, it clears the Timer and Counter concepts in an easy way.The circuit comprises of various components like 555 Timer IC, Decade counter (CD4017), LEDs, Resistors, Capacitors, Wires & a 9V battery. The monolithic integrated circuit 555 timer can be used as square-wave generator, linear saw-tooth generator, pulse generator, time delay generator, etc. here we use it to generate square waveform i.e. it is used in the Astable Mode with a duty cycle of 66.6%.The 8 LEDs could be arranged in any pattern and thus be used as a decorative Light Toy in your living room.

Children like to watch cartoons movies or any other their favourite show on the television and do not pay attention on their studies even at the time of examination. So to keep eye on children we have design a parental control device. When the children in your home hold the remote of the television to on the TV or want to change channel and press any button of the remote then a loud sound would be generated by the device. And these will let you know that your child has tried to switch on the TV. The main advantage of these circuit is that you can easily do your work without any trouble as it produces loud noise so you can hear the noise while working in the kitchen or while sitting in the nearby room.

Controller is actually a combination of two circuits – driver circuit and Switching circuit. Driver is the actual circuit that drives DC motor and switching circuit decides how DC motor should be driven. So actually, switching circuit is the main circuit that controls the motor. Now there are two parameters of DC motor that can be controlled Speed and Direction.Changing the direction of DC motor is very simple just reverse the supply given to DC motor. For varying speed of motor you have to vary the applied DC voltage. One well known method widely used in industries is Pulse Width Modulated (PWM) speed control of DC motor also known as chopper control.

The 8-LED Flasher is built around Timer and Counter ICs. It Flashes 8 LEDs sequentially and the flashing speed can be controlled by a potentiometer. This can be used as a design pattern for decoration. But theoretically, it clears the Timer and Counter concepts in an easy way.The circuit comprises of various components like 555 Timer IC, Decade counter (CD4017), LEDs, Resistors, Capacitors, Wires & a 9V battery. The monolithic integrated circuit 555 timer can be used as square-wave generator, linear saw-tooth generator, pulse generator, time delay generator, etc. here we use it to generate square waveform i.e. it is used in the Astable Mode with a duty cycle of 66.6%.The 8 LEDs could be arranged in any pattern and thus be used as a decorative Light Toy in your living room.

This circuit responds to the change in light illumination in the form of varying frequency which can be observed through a flashing LED as output. The idea of [[wysiwyg_imageupload::]]this project is to use an LDR in place of a fixed value resistor which in turn generates a particular frequency. The generated frequency corresponds to the light conditions of the ambience.This concept finds popular application in motor speed control where the output is connected to motor driver circuit. Disco light is another interesting application of the idea where the lighting pattern keeps on changing. The circuit of this project uses NE555 to generate a continuous series of pulses in astable mode. The frequency of these pulses is obtained based on values of two resistors and a capacitor. Keep on reading to find out more information on the circuit and its working.

白天和黑夜指示项目的主要目的是帮助我们在夜晚自动下降时打开灯光，并且随着白天和黑夜指示器的黎明设置会自动从灯光下熄灭，并播放音乐早晨的唤醒警报。该项目的另一个功能是，在夜间没有照明的时候，夜灯会自动打开。在此电路的帮助下，您无需在夜晚或早晨打开或关闭灯光。

RPM计数器用于测量电动机（AC/DC）或任何旋转对象的速度。它们测量并指示电动机的当前旋转速度。它们在电动机的速度控制和关闭循环控制系统等应用中非常重要。这样的工业RPM计数器非常准确地由微控制器或微处理器组成。

这里呈现的电路使用钥匙串激光器（在市场上很容易获得）将脉冲无线传输至长距离（超过20米）。发射器会产生馈入激光的连续脉冲。激光以脉冲频率闪烁并发出光脉冲。LDR在接收器侧，检测到该光脉冲并在输出下再现。因此，可以在接收器侧至更长的距离接收在发射器侧生成的相同的脉冲。首先，该项目所需的第一件事是准备激光。因此，让我们从如何准备激光开始。市场上可用的激光钥匙链就是这样。为了为该项目做准备，我们需要取出其阳极和阴极端子以提供脉冲。为了从钥匙扣的背面删除按钮单元格和钥匙串部分。您会看到一个小弹簧，这是阴极终端。 Connect one wire with this as shown in the figure below.

询问表示幅度振幅换档键合（也称为On-Off Keying）。这是用于使用高频载体信号传输数字数据的调制方案之一。这是非常简单和流行的方法。It transmits 1’s and 0’s of Digital Data by transmitting carrier or no carrier like · Bit 1 (logic high) is Transmitted with carrier frequency Fc· Bit 0 (logic low) is Transmitted with no carrierMeans series of bits – bit stream is transmitted as carrier ON and carrier OFF. That’s why it is also known as ON-OFF keying.

This project demonstrates how pulses can be transmitted from one place to another place wirelessly using light as medium. One LED is connected at the transmitter side that blinks at frequency of applied pulses. At the receiver side, Light Dependent Resistor (LDR) is used to receive light pulses. IC555 is used at both ends. At transmitter side it is used to generate continuous pulses with variable frequency output from 1 Hz to 10 Hz. At receiver side it is used to generate same pulses as per the trigger input applied by LDR. Note – for visual effect (demonstration) the pulse frequency is kept low. The frequency can be kept high in terms of KHz also.

The circuit presented here rotates stepper motor and varies its RPM (speed). It does not use any micro controller (or micro processor) or any programmable digital device also it does not require any software program to generate sequence of pulses. It drives stepper motor using simple, easily available and commonly used components and ICs like IC555, decade counter, OR gate, current driver chip etc. That is why the name given simple stepper motor driver.

此处显示的电路从00到99，并在两个七个段显示器上显示。它可以在自动模式下作为免费运行计数器起作用，也可以在按钮时手动计数。在自动模式下，它以1 Hz的速度连续脉冲并连续计数。这意味着计数在每秒或换句话说中都会在几秒钟内显示时间。可以通过更改脉冲频率来更改此计数率。在手动模式下，手动按下按钮时，计数会增加。因此，根据手动要求，它可用于计数高达100（从0到99）。计数器电路由十年计数器兼显示驱动程序芯片CD4026组成。使用IC555构建脉冲电路。该电路可用于许多应用程序，例如对象计数器，频率计数器，RPM计数器，停止观察计时器，代币计数显示等。