Arduino Based Lie Detector

light detector circuit using arduino

We have previously posted the the project lie detector, now here is is also a lie detector  using arduino.  Here is a simple tutorial to build a simple lie detector which will give visual indication  through LED arrangement whether the person speaks lie or truth.  The project uses a arduino duemilanove or uno. So the project is based on arduino. But our final circuit will be standalone circuit without attached arduino programmer. Circuit Description: Wiring diagram is very simple, we simply connected three LED to 3 different digital pins as…

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8W + 8W Stereo Amplifier Circuit with Graphic Equalisers

circuit diagram of 8W + 8W stereo amplifier

Various kinds of stereo amplifier are readily available in market. But if we ask for good quality stereo amplifier with graphic equaliser facility, it’s price become very high. The cheaper varieties are generally based on discrete transistors, and suffer from drawback such as uncontrolled hum, ineffective tone control, poor base response, thermal runway etc. the use of inter-stage transformers in such circuits reduces their versatility. Here you find the tutorial to build 8W + 8W Stereo Amplifier with Graphic Equalisers. Features | 8W + 8W Stereo Amplifier Circuit with Graphic Equalisers…

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Automatic Voltage Stabilizer Circuit

circuit diagram of automatic voltage stabilser

The project posted here is called an automatic voltage stabilizer circuit which solves almost all problems faced in the normally available stabilizer efficiently. With the help of the automatic voltage stabilizer circuit, we can keep the constant voltage at 230V when the voltage goes low as 170V and high as 250V automatically. The working strategy of the Automatic Voltage Stabilizer Circuit The working strategy of the circuit is very simple, this circuit energized one relay at a time from 170V AC upwards, and all relays and energized when 230V AC…

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Overvoltage Protection Circuit

circuit diagram of over-voltage protection circuit

Multiple appliances have been born to ease human efforts. And in the same run, numerous protective circuits are designed to ensure a long lifespan of those devices. We have seen those circuits claiming to protect appliances like refrigerators and air-conditioners from voltage fluctuations and brown-outs. An overvoltage protection circuit has been presented here serving multi-purpose security; under-voltage protection, switch-on delay, and regulation. Description of Overvoltage Protection Circuit Do not get worried with the overvoltage protection circuit diagram, though it looks complex, the circuit comprises building blocks we have been familiar…

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Luggage Security System

suitcase arrangement

Introduction to Luggage Security System Number of thefts and robbery has increased to a greater extent. Unemployment, poverty might have been the cause for this but still stealing others property is a serious crime. The only way to stop this is by alerting people themselves with proper security arrangements. Bus hijacking is what we heard commonly of, this is where the fear of crime lies. We have seen people stepping ahead for protection, they use chains, lock as security arrangements to secure their luggage. This might be a nice try,…

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High Current Regulator Circuit

linear high current regulator circuit

The high current regulator circuit can be delivering up to 3-amp load current continuously. The output voltage can be set in the range of 4V to 22V. Fine variation in the output voltage can also be done using a potentiometer VR3. The output current, ranging from 350mA to 3000mA can be varied by potentiometer VR1. Circuit Description of High Current Regulator Circuit The high current regulator circuit given here utilizes all the advantages of the operational amplifier LM3140 (IC1). It has very high input impedance, high gain, high CMRR, low…

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Speech Filter Circuit

circuit diagram of speech bandpass filter using LM387

A speech filter circuit is a broadband filter and is also called a wide bandpass filter circuit because its bandwidth is restricted to the speech frequency. It can be formed by simple cascading high pass and low pass section and is generally the choice for simplicity of design and performance through such a circuit can be realized by a number of the possible circuits. The butter-worth filter is generally used in audio systems which are characterized by a maximally flat-flat filter. Description of Speech Filter Circuit: A speech filter using…

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24 Hour Digital Clock and Timer Circuit

digital timer cum clock circuit

Electronic circuits are usually designed for a specific purpose, which means one circuit performs only one task, in general cases. This circuit here, “24-Hour Digital Clock and  Timer Circuit” is a simple circuit with two different applications as reflected through the name 24-hour clock and a timer. The Circuit of a versatile 24-Hour Digital Clock and Timer Circuit is described below in detail. First, let’s go with some of its unique features. Various Other timer and clock circuits are posted in bestengineeringprojects.com Industrial Timer Circuit Countdown Timer using Arduino Programmable…

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DTMF Based Remote Control System

dtmf based remote controller transmitter unit

Different gadgets have been introduced to meet our requirements ranging from basic needs to classy needs of humans. With this development in recent years, day by day people has grown more sophisticated. Putting human comfort as a main concern, hereby we have presented a circuit to remotely control several electrical or electronic gadgets connected to it. The unique feature of the circuit DTMF-based remote control system in comparison to other remote control systems like IR remote control is that this circuit employs FM transmission and reception, for this reason, it…

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Pest Repeller Circuit

circuit diagram of pest repeller

No matter how far we try to escape from pest’s trap or we attempt to clean the surrounding around us, we get eventually bothered being followed everywhere from kitchen to every corners of our house. Different pest repeller circuits have been developed claiming to escort people through this problem. However, pest repeller circuits thus built are found to have low power output resulting poor effectiveness. And, this error gives no solution to our trouble. With this point as our main concern, we have presented a powerful pest repeller circuit that…

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