Electronics Mini projects

November - 10 - 2011
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Mini Projects

CircuitsToday is listing some free engineering mini projects that can be presented and designed by students for their exams. These mini projects are applicable for B-Tech/BE engineering students from various streams like Electronics and Instrumentation (EI), Electronics and Communication (ECE), Electrical Engineering (EEE), diploma and so on. Though the electronic circuits may look complex, they are explained in detail along with a circuit diagram, and are explained with links of all devices that are used in the circuit. Please note that these projects are meant for students, hobbyists and enthusiasts. If there are any doubts regarding the circuit, feel free to comment on the post. You can also bring in any modifications you want, and ask us if you have doubts. Furthermore, please go through the existing comments to get a better idea of the electronics mini project topics. 

1.       Street Light Circuit

This minor mini project is used to design a street light that brightens up when night falls and automatically turns OFF when day light comes in. In order to detect the amount of light that is needed to decide when to cut-off the circuit and later activate it is done with the help of a sensor called Light Dependent Resistor (LDR). The main principle used behind the LDR is that, the presence of light causes the resistance of the sensor to go low. You can modify he circuit by placing LED’s instead of the 230 volt lamp. To know more about it, check out the comments given in the circuit. The circuit is comparatively easy to design, and further modifications can be made according to your choice.

2.       Battery Charger Circuit Using SCR

This is one of the most basic and best mini projects in electronics. A Silicon Controlled Rectifier (SCR) is used to rectify the AC mains voltage to charge the battery. The circuit consists of basic transistor switching methods and the components are cheap and are available in all electronics shops. A detailed description about the post is also given, which will give you a better idea.

3.       Air Flow Detector Circuit

This simple mini project is used to design an indicator to show the rate of air flow in a given space. The air flow is sensed with the help of an incandescent bulb filament. The variations due to the change of resistance in the bulb due to the air flow are given to the input of an LM339 operational amplifier. The circuit diagram and a better description of the circuit is given in the post above. Further modifications can be brought to the circuit and some of them are given in the comments section.

4.       Water Level Alarm Circuit

This circuit is used to produce an alarm output (bell or light), when the level of water rises above a certain level. This circuit uses a basic astable multivibrator made from a 555 timer IC. A resistance probe is set on a point at which the alarm is to set ON, as soon as the water rises up to that level.  A detailed circuit can be seen in the post above. The number of components needed for this circuit is very less and can be easily assembled on a PCB.

5.       Low Cost Fire Alarm Circuit

This circuit can be used for detecting a fire and producing an alarm, thus alerting the people in the building where it is installed. A transistor sensor called BC177 is used to sense the heat produced due to the fire. A preset level can be kept for the transistor. As soon as the temperature rises above the set preset level, the leakage current of the transistor rises, thus driving the other transistors in the circuit.  A relay is also used to switch the bell load as its output. The components needed for the circuit can be obtained easily and the circuit is easy to design.

6.      Single Chip FM Radio Circuit

This mini project is mainly meant for Btech EC students. An IC called TDA7000 is used for the purpose. The IC is integrated with a Frequency-Locked-Loop system with an intermediate frequency of 70 kHz. There have been many complaints that the IC is obsolete. Please check the comments to know the exact site to buy the IC. For more detailed explanation about the FM radio circuit, please check out the original post.

7.      Digital Stop Watch Circuit

The project consists of a digital watch designed with the help of a 555 timer IC and 4-bit digit counter IC called IC MM&4C926, and also a 7 segment LED display. The circuit can be easily designed and assembled on a printed circuit board. Further instructions and detailed working can be obtained from the original post.

8.      High and Low Voltage Cut-off With Delay and Alarm

This circuit can not only be presented as your mini project, but can also be applied on your home electrical equipments to protect them from over voltage fluctuations. The circuit requires very simple components like a monostable multivibrator using a 555 timer, a few transistors, and some diodes, relays ad LED.

The detailed explanation is given in the post above, and if you wish you can easily modify the circuit to make it an automatic voltage stabilizer.

9.      Light Activated Switch Circuit

This circuit uses an LM 311 comparator IC and a light dependent resistor as its sensor. The output of the LDR is given to the inverting input of the comparator. The resistance remains high when there is no light and the resistance drops as soon as light falls on it. This lessens the voltage at the inverting input and thus the comparator produces a high output which turns a transistor and thus the relay on. A much more detailed working can be obtained from the original post.

10.  Mobile Incoming Call Indicator

This circuit can be used to escape from the nuisance of mobile phone rings when you are at home. This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated.

Latest Mini Projects:- 

1. Water Level Controller using Micro Controller – AT89S51

This is a classic mini project for electronics engineering students. Developed using AT89S51 (a version of 8051 from Atmel) with a well explained circuit diagram and program. We have tested and verified this circuits functioning in our lab. The program is written in assembly language using the MCS-51 instruction set.

2. Frequency Counter Circuit using Avr Atmega8 controller

In this project, you can make a frequency counting device/system.We have developed this using Avr Atmega8 microcontroller. We have given the complete circuit diagram, software codes and other necessary information to make this project a reality.  If you are not familiar with Avr Atmega8 controller, we have developed a complete tutorial to learn Avr from ground. 

Note:- If you have any doubts, please ask in the comments section of the corresponding post

3. Digital Voltmeter using 8051 Microcontroller – AT89S51

In this project, you can make a simple digital voltmeter application which can measure upto 5 volts (0 to 5 volts). The circuit is developed using ADC0804 and AT89S51 micro controller. The output is displayed using two 7 segment displays. The software is developed in assembly language.

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