Category: Electronics Projects

Earth Quake Alarm Circuit

Engineeering Projects
design of earthquake sensor

Here is a simple project called earth quake alarm circuit. This circuit is divided into two sections. Geo mechanical detector (Earth quake sensor) Alarm circuit The earth quake alarm circuit is based on the principle that earth quake create slow and suddenly vibration. In order to detect this vibration geo mechanical detector is used. The construction of geo mechanical detector is shown in figure 2. Alarm Circuit | Earth Quake Alarm Circuit The alarm circuit is built around dual input, 4 NAND IC (CD4011) and a NPN transistor. Input of…

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Tone Control for Guitar Amplifier Using 741

Engineeering Projects
circuit diagram of tone controller for guitar amplifier

Simple guitar amplifier circuit consist bass and treble circuit which is not appropriate. A sophisticated guitar amplifier must contain individual control for very string. Here is simple tone control circuit for guitar which has individual string control with bass and treble facility. The circuit of tone control for guitar amplifier is build around two most popular and low cost op-amplifier IC 741. This circuit is designed to control tone of 6-band of frequency 40Hz, 155 HZ, 625 Hz, 2.5 KHz and 10 KHz respectively. This frequency is control by variable…

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Battery Voltage State Indicator using 741

Engineeering Projects
battery voltage state indicator circuit diagram

Here is a simple circuit using op-amp 741 called “Battery voltage state indicator using 741” used to indicate whether the battery is charged or not. The circuit shows three states of battery voltage i.e. charged, discharged, and normal using three different color LEDs (LED1, LED2, and LED3). you may also like other battery state indicator circuit Battery level state indicator (Designed using general-purpose NPN transistor 2N2222, indicate two states of battery i.e. undercharged and overcharged). 10 Level battery Charge Indicator Circuit (Designed using comparator IC LM3914, used to indicate the…

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Arduino Based Lie Detector

Engineeering Projects
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

Engineeering Projects
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

Engineeering Projects
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

Engineeering Projects
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

Engineeering Projects
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

Engineeering Projects
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

Engineeering Projects
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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