Free Electronics Mini Project Circuits

Here we have presented a list of various mini electronics projects circuits that are published on this blog. This is page is more helpful for the visitors in getting an idea about the different electronics circuits that are present in this blog. You may click on any of the following list of projects to get detailed explanation about that particular project and its circuit diagram.

Electronics Mini Projects Free Circuits

Free Project Circuits from ElectronicsHub.Org

List of Electronics Mini Project Circuits:

SNO
Mini Project Name
1
Water Level Indicator: This Water Level Indicator project employs a simple mechanism which helps to detect and indicate the water level in an overhead tank or any other water container. It can be used in Hotels, Factories, Homes Apartments, Commercial Complexes, Drainage, etc.
2
Password Based Door Lock System using 8051 Microcontroller: This system demonstrates a password based door lock system wherein once the correct code or password is entered, the door is opened and the concerned person is allowed access to the secured area. After some time, the door would be closed. Read this post completely to get more information.
3
Cell Phone Controlled Robotic Vehicle: This is simple DTMF based Cellphone controlled robotic vehicle circuit without using microcontroller. It can be used in industries and surveillance systems.
4
Human Detection Robot using 8051 Microcontroller: The main principle of the circuit is to detect the human using human detection sensor. The wireless robot is operated manually using PC. The wireless technology used here is Radio Frequency technology. The data is transmitted to receiver through RF.
5
SMS Controlled Robot: GSM controlled robot or SMS controlled robot is a wireless robot which performs the necessary actions by receiving a set of instructions in the form a Short Message Service (SMS).
6
Remote Password Operated Electronic Home Appliances: This circuit explains you how to control the electrical appliances using an Android device. Here, Bluetooth module is interfaced to 8051 microcontroller. This Bluetooth receives the commands from the Android application device using wireless communication.
7
Metal Detector Robotic Vehicle: Land mines buried under the ground causes threat to the lives and affect the economy of the nation. Detection and removing of these mines manually is a dangerous task. So, we use a metal detection robot which works on RF technology.
8
Water Level Alarm Using 555 Timer: This is a simple and low cost hardware project using a 555 timer circuit. The aim of this project is to design a water level detecting alarm with simple and low cost hardware without compromising on the performance of the device.
9
Speed Control of DC Motor Using Pulse Width Modulation: This pulse width modulation technique is the more efficient way to proceed to manage the speed of our DC motor manually.
10
Sun Tracking Solar Panel: This article describes about circuit that rotates solar panel. This Sun tracking solar panel consists of two LDRs, solar panel, stepper motor and ATMEGA8 Microcontroller.
11
Bidirectional Visitor Counter using 8051: This Bidrectional Visitor Counter Circuit is helpful to count the number of persons entering or leaving a room and to display it on a screen.
12
Password based Circuit Breaker: This password based circuit breaker project is built using 8051 controller and is used to switch off the power supply to the line by entering a password.
13
Temperature Controlled DC Fan using Microcontroller: The main principle of the circuit is to switch on the fan connected to DC motor when the temperature is greater than a threshold value.This can be used in home applications and in cpu to reduce heat.
14
Auto Intensity Control of Street Lights: This is a simple circuit that automatically controls the intensity of street lights which is designed using microcontroller and LEDs.
15
Line Following Robotic Circuit using ATMega8 Microcontroller: This line follower robot is a basic robot that follows a specific path indicated by a line having some particular width.
16
Digital Tachometer using 8051 Microcontroller: Here we designed a simple non contact tachometer using microcontroller which can measure speed with an accuracy of 1 rev/sec.
17
5 Channel IR Remote Control System using Microcontroller: This article is aimed to design and demonstrate a simple 5 channel remote control system to drive five loads. This circuit works on the principle of IR communication.
18
Bipolar LED Driver Circuit: This bipolar LED driver circuit is very useful at the places where flashing of light is required, as in beacon flashing. This circuit can be mainly used for indication purposes.
19
Celsius Scale Thermometer using AT89C51: This Celsius Scale Thermometer circuit is designed using at89c51 and lm35. This circuit works on analog to digital conversion principle. It can be used at homes, mobile places like cars to keep a track of the temperature.
20
Density Based Traffic Signal System using Microcontroller: In this system, we use IR sensors to measure the traffic density. We have to arrange one IR sensor for each road; these sensors always sense the traffic on that particular road. All these sensors are interfaced to the microcontroller. Based on these sensors, controller detects the traffic and controls the traffic system.
21
Automatic Washroom Light Switch: This is a simple but very useful circuit in our real life which helps to automatically turn On the lights when a person enters the washroom and it automatically turns Off the lights when he leaves it.
22
Automatic Door Bell With Object Detection: This automatic doorbell with object detection circuit helps to sense the presence of a person or an object automatically and rings the doorbell.
23
Boolean Algebra Calculator: This Boolean algebra calculator is an interesting project which is more useful in our real life by working as a portable calculator to simplify the Boolean expression on the fly. In our circuit, we use Boolean algebra simplification methods like the Quine-McCluskey algorithm to simplify the Boolean expression and display the output on the display.
24
Auto Night Lamp using High Power LED: This Auto Night Lamp is an interesting circuit which helps to turn ON the LED lights interfaced to it at night time and it turns OFF the lights automatically when it is day.
25
Mobile Jammer Circuit: This circuit is used to block the signals of cell phones with in the range of 100 meters. This circuit can be used in TV transmission and also for remote controlled toys or play things.
26
Unbiased Digital Dice with LEDs: This is a circuit diagram of digital dice which is nearly unbiased. By using this circuit, there is no chance to cheat as the circuit operates at such a high speed that the circuit is almost imperceptible to the human eye.
27
Metal Detector Circuit: This is a simple metal detector circuit which is very useful for checking the person in shopping malls, hotels, cinema halls to ensure that person is not carrying any explosive metals or illegal things like guns, bombs etc.
28
Panic Alarm: This panic alarm circuit helps us to intimate others regarding our bad situation without any delay. It is more useful when an intruder entering our house or bad health status at which we are unable to intimate to the people around us.
29
Simple 100W Inverter Circuit: This is a small Inverter circuit which converts the direct current (DC) to alternating current (AC).
30
Car Parking Guard Circuit Using Infrared Sensor: This circuit helps the person in the driving seat in such a way that it gives an alarm if there is any obstacle or a wall while parking or while driving in reverse. It is very useful in our real life.
31
Fire Alarm with Siren Sound: This circuit alerts us when there is a fire accident at home by ringing a siren sound instead of a buzzer.
32
Intelligent Unambiguous Night Lamp Switcher: This is the circuit diagram of unambiguous night lamp switch, which turns ON our domestic lights automatically when it is dark, without human interference. It also avoids repeated frequent switching of the devices which is usually ignored in most similar circuits but may have a detrimental effect on our operating devices.
33
Automatic Railway Gate Controller with High Speed Alerting System: The main aim of this project is to operate and control the unmanned railway gate in the proper manner in order to avoid the accidents in the unmanned railway crossing.
34
LED Flasher Circuit: LED Flasher is a simple circuit which will blink the LEDs in regular time period. This circuit can be used for decoration purpose or can be used for a signaling purpose and many more.
35
Dancing Bi-Color LED Lights Circuit: Generally we use small voltage bulbs in the dancing bulbs. This circuit is mainly used in the occasions, decoration articles or in visual indication sign boards etc. In this project, we use bi-color LEDs for sequential running light.
36
Thermistor Temperature Sensing Alarm: This circuit is a temperature sensing as well as alarm circuit. The circuit raises an alarm whenever the temperature crosses a certain limit.
37
Pull Pin Security Alarm System: This circuit helps us to get alerted when anybody picks our pockets or bags. The circuit is very helpful to prevent our goods getting pick pocketed.
38
Auto Turnoff Soldering Iron Circuit: This circuit helps the soldering iron to turn off automatically when it detects overheating and thereby avoids it from getting damaged.
39
Remote Operated Alarm Circuit: This circuit rings an alarm when you point a TV remote at it and press on any button. This can be used as a calling bell to call your assistant.
40
Battery Charger Circuit Using SCR: Here is the circuit diagram of battery charger circuit using Silicon Controlled Rectifier. SCR can be used in half wave rectifier, full wave rectifier, inverter circuits, power control circuits, etc.
41
FM Bugger Circuit: Here is small circuit with which you can listen to another people conversation from long distance using the normal FM radio set. This FM bugger circuit is kept in room where you want listen the conversation. You can listen to this conversation using the normal FM radio set.
42
Cell Phone Detector: This is a simple circuit which helps to detect the presence of an activated cell phone by detecting the signals in the frequency range of 0.9 to 3GHz. It helps in mobile phones tracking which are used for spying.
43

Battery Powered Portable Light: This circuit is more helpful in handling unexpected and undesired darkness in our homes or offices. It provides considerable amount of brightness required to do our daily tasks.
44
IR Remote Control Switch: By using this circuit, we can control any house hold appliance with the help of remote. In this project, there are two parts – one is in transmitting section and the other is in receiving section. Receiving section will be in a stable position which is connected to any load and transmitter will act as a normal remote.
45

Continuity Tester with Melody: This circuit works as a continuity tester device which tests the continuity of the wire at hand. It is an indispensable tool to check broken wires and undesired shorting of wires.
46

Rain Alarm Circuit: Rain water detector will detect the rain and make an alert; rain water detector is used in the irrigation field, home automation, communication, automobiles etc. Here is the simple and reliable circuit of rain water detector which can be constructed at low cost.
47

Automatic Plant Irrigation System: This project circuit is more useful in watering plants automatically without any human interference. It is more useful when the owner is not present in the home for few days.
48

Hot Water Geyser Controller Circuit: This circuit is made to turn OFF geysers as soon as our water gets hot and are ready for bathing.
49

Lead Acid Battery Charger Circuit: Lead Battery is a rechargeable battery and is more useful in our real life as it will dissipate very little energy, it has very low energy to weight ratio, it can deliver high current, can work for long time with high efficiency and is very low cost.
50

Motion Detector Circuit: The motion detector is not only used as intruder alarm but also used in many applications like home automation system, energy efficiency system, etc. The motion detector will detect the motion of the people or objects and give the appropriate output according to the circuit.
51

Touch ON and OFF Switch Circuit: This Touch ON/OFF Switch circuit is more useful in such a way that we can automatically ON or OFF any switch by touching a device without moving from our place.
52

USB Mobile Charger Circuit: This circuit is useful in charging the mobiles through USB outlet present in our laptops and PCs. For the charging of your mobile phone, this circuit provides you a regulated voltage of 4.7 volts.
53

Security Alarm Circuit: This circuit helps you to guard your precious documents as well as jewellery from intruders or theft. All you need is to just place this circuit in front of the locker or below the mat so when any unknown person come and walk over the switch, the circuit will trigger and sound of alarm comes.
54

Mosquito Repellent Circuit: Here is the simple electronic mosquito repellent circuit which can produce ultrasound in the frequency range of 20-38 kHz, which can scare away mosquitoes.
55

Simple FM Radio Jammer Circuit: This is a Jammer circuit which is used to block the signals. Jammer circuit produces the high frequency signal which will confuse the receiver of particular system from receiving the signal, even though circuit is working properly, user of the system feels that circuit is not working properly.
56

Automatic Street Light Controller Circuit Using Relays and LDR: This circuit helps in automatically turn ON/OFF the street lights using relays and LDR. The whole circuit is based on IC CA3140.
57

Battery Charger Circuit: This battery charger circuit works on the principle of controlling switching of an SCR based on charging and discharging of battery.
58

Interfacing 16x2 LCD with 8051: This is a simple circuit diagram which helps to describe interfacing of 16X2 LCD module to AT89C51which is a 8051 family microcontroller.
59

PWM LED Dimmer Using NE555: The Pulse Width Modulation (PWM) plays an important role in controlling the circuits. We use this PWM to dim the intensity of light of the LED.
60

Simple Fire Alarm Circuits: Here are two simple fire alarm circuits which are used to detect the fire automatically and inform to the people immediately with an alarm.
61

Wireless Switch Circuit using CD4027: This is a simple circuit which needs no physical contact with the appliance. In this circuit, all you need is to pass your hand above LDR to ON or OFF the switch.
62

Electronic Letter Box: This is a simple circuit which helps in finding out any letter dropped in our box by stopping the LED lights attached in this circuit.
63

Clap Switch Circuit for Devices: This is another simple but very useful circuit which helps to ON or OFF a device without moving from you place and also helps to control the speed of the electric devices like fan, etc.
64

12v DC to 220v AC Converter Circuit: Here is a simple voltage driven inverter circuit which converts 12v DC signal to single phase 220v AC using power transistors as switching device.
65

FM Transmitter Circuit: Here we built a wireless FM transmitter which uses RF communication to transmit the medium or low power FM signal. The maximum range of transmission is around 2 km.
66

100w Subwoofer Amplifier Circuit: Here is the circuit diagram and working of 100w subwoofer amplifier circuit. A Subwoofer is a loudspeaker which produces audio signals of low frequencies.
67

DTMF Based Home Automation System Circuit: This is a simple and very useful circuit in our real life named DTMF controlled home appliances system. It helps to control the home appliances using DTMF technology.
68

Street Lights that Glow on Detecting Vehicle Movement: This article describes about the circuit that switches the street lights on detecting vehicle movement and remains off after fixed time. This system controls the street lights using light dependent resistor and PIR sensor.
69

555 Timer IC Testing Circuit: This is a simple 555 IC testing-circuit which tests your entire 555 timer IC. So before using your IC, you may check whether your IC is good or bad by using this circuit.
70

Curtain Opener/Closer Circuit: This circuit will open and close the curtain of your home and office just by pushing a switch. So with the help of this unique circuit, we do not need to move from one place to open and close the curtain.
71

Variable Power Supply and Charger: This is a circuit which helps to check or test your electronic projects and also to charge the Mobile phone batteries. This circuit can also work as an emergency light.
72

LED Running Lights Circuit: This is a simple circuit consists of 9 LED lights in knight rider scanner mode. It will present an eye catching look as the LED initially travel in the one way and then travel reverse in the similar direction.
73

Luggage Security Alarm: This is a simple alarm circuit which helps in ringing a warning alarm when someone tries to steal the luggage.
74

9 Way Clap Switch Circuit: This circuit helps you to manage your appliances in your home by just clap without moving from your bed.
75

12V to 24V DC Converter Circuit: This is another kind of circuit which helps to convert 12V DC current to 24V DC current.
76

230V LED Driver: Here we design a simple circuit driving a series of LED from 230V AC. This is accomplished using a capacitor based power supply. This is a low cost and efficient circuit and can be used at homes.
77

3X3X3 LED Cube: This is a simple a simple LED cube circuit designed without using microcontroller. It is based on the principle of driving LEDs using the clock pulses.
78

Monostable Multivibrator Circuit Operation: Here is the monostable multivibrator circuit diagram and working. Multivibrator is an electronic circuit which will work as two stage amplifier operating in both stable and astable mode.
79

Interfacing16X2 LCD with PIC Microcontroller: This is a circuit which helps in interfacing 16×2 LCD to PIC18F4550 microcontroller which is of family PIC18F.
80

Morse Code Generator Circuit: This is a circuit used to generate morse code. Morse code is very old and versatile technique to send text messages using wireless media.
81

555 Timer in Monostable Multivibrator Mode: The circuit is triggered by a falling edge, that is, by a sudden transition from HIGH to LOW. The trigger pulse, produced by pressing the button, must be of shorter duration than the intended output pulse.
82

555 Timer as an Astable Multivibrator: In this circuit, There are three resistors named R inside it and all have equal values. These form a voltage divider having reference voltages of 1/3 and 2/3 of Vcc (the power supply). The logic state of the flip flop is controlled by the reference voltage which is given to one of the inputs of both two comparators.
83

Mains Operated LED Light Circuit: This is a simple circuit which is more useful to save our resources, energy and money by installing in your homes.
84

LED Lamp Dimmer Circuit: In this circuit, at the starting LED glows slowly, then grown brighter and once again slowly it became dim. The basis of the whole circuit is an operational amplifier IC named LM358.
85

Variable Voltage Power Supply from Fixed Voltage Regulator: This Voltage regulator circuit is used to get fixed voltage at the output without depending on the input voltage.
86
LED Christmas Lights Circuit: This is a simple circuit used to decorate your house by building christmas lights using LEDs. The lights will get ON at night and OFF in morning time.
87
Audio Equalizer Circuit: The circuit is used to change the tune/melody into a different pitch level by devoid of loss in the tune. It is mainly useful to music lovers.
88
Air Flow Detector Circuit: This Air flow detector circuit can be used to detect the flow of air in areas like car engine. It can also be used as temperature detector.
89
150W Power Amplifier Circuit: Here we designed a power amplifier circuit using push pull class AB configuration to derive a power of 150W to drive a load of 8 Ohms (speaker).
90
7 Segment LED Display Decoder: This is the circuit diagram of display decoder which is used to convert a BCD or binary code into a 7 segment code used to operate a 7 segment LED display.
91

Digital Temperature Sensor: The main principle of this circuit is to display the digital temperature value. These are mainly used in environmental applications.
92
Digital Stopwatch Circuit: This is a simple circuit that displays count from 0 to 59, representing a 60 second time interval. It consists of a 555 timer to produce the clock pulses and two counter ICs to carry out the counting operation.
93
Toy Organ using 555 Timer IC: This is the circuit diagram of simple Toy Piano using 555 Timer IC. It produces different tones or sounds depending on the frequency range.
94
RFID based Attendance System: This simple RFID based attendance system is designed using ATmega8 Microcontroller and is mainly used in educational institutions, industries, etc. where authentication is needed.
95
Low Power Audio Amplifier using 555 Timer: This is a simple low power audio amplification circuit designed using 555 timer. It can be used to develop low power music systems used in vehicles.
96
Interfacing 16X2 LCD to AVR Microcontroller: This is a circuit which helps in interfacing 16X2 LCD with AVR Microcontroller. The Atmega16 belongs to the AVR microcontroller family.
97
SR Flip Flop with NAND and NOR Gates: SR Flip Flop, also known as SR latch is the most vital as well as broadly used Flip Flop. Get an idea about design of SR Flip Flop with NAND and NOR Gates.
98
JK Flip Flop using CD4027: CD4027 is a JK flip flop that is generally used for data storing. Get an idea about how to build JK Flip Flop with CD4027.
99
Polarity cum Continuity Tester: With the help of this circuit, we can also identify whether the components we are using in our circuit are good or bad before mounting them on the PCB.
100
Reaction Timer Game Circuit: This is a simple and funny game circuit which contains 10 LEDs that are moving in an arbitrary fashion and we have to target a particular LED given by your challenger.
101
Multiplexer and Demultiplexer: A multiplexer is a circuit that accepts many inputs but gives only one output where as a demultiplexer accepts only one input and gives many outputs. Get an idea about their circuit diagram and pin diagrams in this post.
102
Understanding 7805 IC Voltage Regulator: This is a circuit diagram of 7805 IC which is a 5v DC regulated IC. It is very flexible and is employed in many circuits like a voltage regulator.
103
Basic Logic Gates Using NAND Gate: We are all well known that NOT, AND, OR are the basic logic gates. Here we have shown how to design these basic logic gates using one of the universal gates - NAND Gate.
104
Construction of Basic Logic Gates using NOR Gate: Here, we have shown how to construct the basic logic gates - NOT, AND, OR gates using NOR Gate which is one of the universal gates.
105
Police Siren Circuit using NE555 Timer: This circuit produces a sound similar to the police siren. You may also get detailed information about pin diagram and internal block diagram of NE555 timer.
106
100W MOSFET Power Amplifier Circuit: A power amplifier circuit using MOSFET has been designed to produce 100W output to drive a load of about 8 Ohms.
107
Digital Voltmeter Circuit using ICL7107: Here we designed a analog to digital converter working as a digital voltmeter using a low power three and half digit A/D converter ICL7107 having internal 7 segment decoders, display drivers, a reference and a clock.
108
8 Channel Quiz Buzzer Circuit using Microcontroller: We built the circuit using a microcontroller which scans the input from push buttons and displays the corresponding number on a display device.
109
2 Digit Up Down Counter: The main principle of this circuit is to increment the values on seven segment displays by pressing the button. This circuit can be mainly used in scoreboards.
110
Bike Turning Signal Circuit: The objective of this circuit is to indicate left or right turn for bike/vehicle. Two identical circuits are needed, one is for left and the other is for right. The main heart of this circuit is 555 timer.
111
Automatic Changeover Switch: This is a simple automatic changeover circuit in which DC load like a series of LEDs are driven either by a battery or an AC-DC power supply.
112
UP/DOWN Fading LED Lights: This is a simple up/down fading LED lights circuit which can be used in shopping malls, home and security applications."/>
113
Police Lights using 555 Timer: This circuit simulates the police car lights by alternate flashing. This circuit flashes red LEDs for three times and blue LED’s for three times. This flashing action performs continuously. This circuit uses 555 timer and a decade counter.
114
PWM based DC Motor Speed Control using Microcontroller: Here is a simple DC Motor speed control circuit designed using AVR Microcontroller. Here we use a technique called PWM (pulse width modulation) to control the speed of DC motor.
115
Ding Dong Sound Generator Circuit: This is ding dong sound generator circuit is designed using 555 timer IC in astable mode. It can be used as doorbell. With some modifications, it can be used to produce different sounds. Read this post for complete details.
116
PIR Sensor Based Security Alarm: This article explains about PIR based security system in which PIR sensor is used instead of transmitter or receiver. This saves the power consumption and is low cost. This circuit can be used in the museums to protect the valuable things.
117
TV Remote Control Jammer: This proposed TV jammer circuit confuses the infrared receiver in a TV by producing the constant signal that interferes the remote control signal. If you switch on the circuit once, the TV will not receive any command from the remote. This allows you to watch your own program without anyone changing the channel or volume.
118
Super Sensitive Intruder Alarm: This circuit is designed to alert the user when an intruder enters into the home. If there is any obstacle in front of IR sensor, it generates an interrupt signal. This interrupt signal is given to the speaker to alert the user.
119
Remote Control Circuit through RF without microcontroller: Here we have used RF434 MHz modules to make wireless remote. Using this remote, we can control the appliances within the range of 100 meters. It is used for remote control applications like burglar alarm, car door alarm, calling bell, security systems, etc.
120
High and Low Voltage Cutoff with Delay and Alarm: This high and low voltage cutoff with delay alarm circuit is an advanced automatic voltage stabilizer circuit and is used to protect our home appliances. It's cost is less as compared to voltage stabilizers.
121
Solar Battery Charger Circuit: Here is the simple circuit to charge 6V, 4.5Ah rechargeable Lead-acid battery from the solar panel. This solar charger has current and voltage regulation and also has over voltage cut off facilities. This circuit may also be used to charge any battery at constant voltage because output voltage is adjustable.
122
Car Battery Charger Circuit: This article aims to describe the principle of operation, design and working of a simple car battery charger from AC mains supply and a feedback control section to control the battery charging.
123
Water Level Controller using 8051 Microcontroller: Here we are designing the circuit which is used to detect and control the water level automatically in overhead tank using 8051 microcontroller. It is used in industries to control the liquid level automatically.
124
Dummy Alarm Circuit: The main principle of the circuit is to flash an LED for every 5 seconds. The circuit consists of 7555 timer IC as main component.
125
Reverse Parking Sensor Circuit: If you are a new driver then it is very difficult to judge the distance while parking the car. Reverse parking sensor circuit solves this problem by indicating the distance with the help of three LED’s. We can easily arrange this system at the back side of the car.
126
Automatic LED Emergency Light Circuit: This is the simple and cost effective automatic emergency light circuit with light sensing. This system charges from main supply and gets activated when main supply is turned OFF. This emergency lamp will work for more than 8 hours.
127
One Transistor Electronic Code Lock System: The main principle of this circuit is that the door lock opens only when the buttons are pressed in an order. The transistor and diode plays a main role in the circuit.
128
Automatic Battery Charger: This charger automatically shut off the charging process when battery attains full charge. This prevents the deep charge of the battery. If the battery voltage is below the 12V, then circuit automatically charges the battery.
129
Light Activated Switch Circuit: The main principle of this circuit is to switch ON the light when the LDR is illuminated. This circuit can be used in security applications like when there is darkness on the LDR, it stops lighting.
130
Remote Operated Spy Robot Circuit: This is a simple spy robot circuit which can be controlled by the remote. The maximum controllable range is 125 meters. It is used to observe the behavior of wild animals where human beings cannot reach.
131
Digital Voltmeter using 8051 Microcontroller: This is a simple digital voltmeter circuit designed using 8051 microcontroller. This circuit measures the input voltage from 0V to 5V. Here, the input voltage should be DC voltage to get the accurate output on LCD.
132
Ultrasonic Rangefinder using 8051: This circuit explains you how to measure the distance using 8051 microcontroller. This ultrasonic range finder system measures the distance up to 2.5 meters at accuracy of 1 cm.
133
Stepper Motor Interfacing with 8051 Microcontroller: The main principle of this circuit is to rotate the stepper motor step wise at a particular step angle. The ULN2003 IC is used to drive the stepper motor as the controller cannot provide current required by the motor.
134
Frequency Counter Circuit: Here we design a simple frequency counter system using two timers and two counters. While one of the Timer IC is used to produce clock signals, the other is used to produce the time limited signal of one second.
135
Delay using 8051 Timers
136
Interfacing 7 Segment Display to 8051: This article describes you how to interface seven segments to AT89C51 microcontroller. This system displays the digits from 0 to 9 continuously with a predefined delay.
137
LC Meter using 555 Timer: This is a simple LC Meter circuit designed using 555 Timer and 8051 microcontroller. It is mainly used to measure value of a reactive element like a capacitor or an inductor.
138
TV Transmitter Circuit: The main principle of this circuit is to transmit the audio and video signals. Here audio signals are frequency modulated and video signals are PAL modulated. These modulated signals are applied for the antenna.
139
DC Motor Interfacing with 8051 Microcontroller: Here is a simple but very useful circuit in our real life named interfacing DC motor with 8051 microcontroller. It describes you how to control the DC motor using AT89C51 controller.
140
Stun Gun Circuit: This Stun gun circuit is mostly used as a weapon to stun or send shock waves to the target with the intention to weaken or paralyze it.
141
Transistor Intercom Circuit: This transistor intercom circuit is a simple two way intercom circuit which is used for the dual purpose of sending as well as receiving signals.
142
LED Interfacing with 8051: The main principle of this circuit is to interface LEDs to the 8051 family micro controller. Commonly, used LEDs will have voltage drop of 1.7v and current of 10mA to glow at full intensity. This is applied through the output pin of the microcontroller.
143
Wailing Siren Circuit: The main principle of this circuit is to produce a wailing siren. The 555 timer IC is operated in astable mode. When the switch is pressed, speaker produces high pitch siren and when it is released, its pitch decreases and is switched off after 30 seconds.
144
Audio Tone Control Circuit: This article explains you how to design an audio tone control circuit with the gain of around 25. This design needs less number of components and it is cost effective.
145
FM Remote Encoder/Decoder Circuit: This is a simple post which shows you how to design FM remote encoder and decoder circuit using RF600E and RF600D ICs. This pair of encoder and decoder ICs establishes the communication with high level security. The operating voltage of these ICs is from 2V to 6.6V DC.
146
Wireless Mobile Battery Charger Circuit: This circuit mainly works on the principle of mutual inductance. This circuit may be used as wireless power transfer circuit, wireless mobile charger circuit, wireless battery charger circuit, etc.
147
Battery Level Indicator: This article explains you how design battery level indicator. You can use this circuit to check car battery or inverter. So by using this circuit, we can increase the lifetime of battery.
148
FM Radio Circuit: FM Radio circuit is the simple circuit that can be tuned to the required frequency locally. This article describes the circuit of FM radio circuit. This is a pocket sized radio circuit.
149
LED Lamp Circuit using USB Port: This is a simple USB LED Light circuit which produces an output of 5v. It may be used as emergency light and also as a reading lamp.
150
Interfacing GPS with 8051 Microcontroller: In this interfacing of GPS with 8051 circuit, GPS module calculates the position by reading the signals that are transmitted by satellites.
151
How to Interface Real Time Clock with PIC18F: Get an idea about RTC, PIC Microcontroller pin diagram and how to interface RTC with PIC18F. RTC is an integrated circuit which keeps track of current time.
152
Random Number Generator using 8051: This circuit helps to generate a random number in between 0 to 100 when push button is pressed and it may be used in the games like monopoly, snake ladder.
153
Active Audio Crossover Circuit: Audio crossover is an electronic filter used in audio applications to send the appropriate signal to the speakers or drivers. This circuit is used in HiFi audio systems to separate the frequency bands from audio signal.
154
IR Audio Link Circuit: This simple IR audio link circuit is used to transmit audio signals wirelessly. This IR audio link is able transmit audio signals up to 4 meters.
155
Cellphone Controlled Home Appliances: This mobile controlled home automation system is designed without using microcontroller. We can also control a robot using this technology by making some modifications.
156
Variable Voltage Power Supply: This helps to design a variable power supply circuit which will provide 0 to 28V at 6 to 8 amps. It can be used in various power amplifiers and oscillators to provide DC supply.
157
Digital Clock using 8051: This circuit displays the time on LCD. For this clock, we can set the time at any instant. Here the clock works in 24 hour mode and the RTC chip is configured by programming 8051 controller.
158
GSM Interfacing with 8051: The main principle of this circuit is to interface a GSM modem with the microcontroller. The microcontroller used is AT89C51 microcontroller.
159
Multi Channel Audio Mixer Circuit: This audio mixing circuit has 2 MIC inputs and 2 line inputs. If you want to increase the input channels according to the application then add same circuit in parallel with the existing circuit.
160
Puff to OFF LED Circuit: The main principle of the circuit is to turn off the LED by a puff. The puff applied to the mic is converted into a voltage whose value is very small. This voltage is amplified and applied to the circuit in order to make the led turn off.
161
Biometric Attendance System: The main aim of this circuit is to take the attendance using biometric method and display when requested. This can be used in educational institutions, industries, etc.
162
Light Activated Alarm Circuit: The main principle of this circuit is to produce sound depending on the light intensity falling on the circuit. As the light intensity falling on the circuit increases, it produces pulses with more duration and thus producing more sound. The main part of the circuit is 555 timer IC.
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Electronic Eye Controlled Security System: This is a simple electronic eye controlled security system circuit designed using 7805 voltage regulator and LDR. It is used in security applications.
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USB Sound Card Circuit: This USB sound card circuit is a device which allows an embedded system to create and record real and high quality sound. Read this post for more details.
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10 LED VU Meter Circuit: VU Meters are used in many applications like discotheques to measure the level of audio signals. Here is the circuit diagram and working of LED VU Meter.
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Hi-Fi Dx Bass Circuit: This Hi-Fi Dx Bass Circuit describes the design, principle and operation of a two stage bass boosting circuit using simple high and low pass filters.
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Wireless Electronic Notice Board using GSM: This wireless electronic notice board using GSM Technology and microcontroller circuit is used to display the data on LCD whatever we sent from the mobile.

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