# Free Electrical Mini Projects Ideas with Circuit Diagrams

Electrical  engineering is a branch of engineering that involves a different power or energy form to run the entire world. Every electrical engineering student needs to work with energies such as solar energy, geothermal energy, wind energy, gas and turbine, etc. If a student wants to work on particular electrical mini projects during his course, In this article, we are providing a few  electrical mini project ideas with circuit diagrams. In this article, we are providing a few electrical engineering project ideas that help students design electrical projects on their own.

## Electrical Mini Project Circuits

Electrical and electronics mini projects can be built using various electrical and electronic components. These circuits are used to design mini projects for EEE students.Here, we have explained some eee mini projects with circuit diagrams.

#### Cell Phone Detector Circuit Diagram

A cell-phone detector circuit uses high frequency ranges from 0.9GHz to 3 GHz. This circuit uses a disk capacitor (C3) 0.22 μF according to the RF circuit to ensure the circuit’s capability to capture the mobile signal. The cell phone detector can sense any activity of a cell phone voice transmission or video transmission including incoming SMS or outgoing SMS. The capacitor C3 should have an 18mm lead length with 8mm spacing between leads to attain the desired frequency. This capacitor acts as a small GHz loop to collect the RF signals. The Op-Amp CA3130 is used as a current to voltage converter. This cell phone detector circuit can be used to confirm the existence of an active cellular phone in the tested area.

#### SCR based Battery Charger Circuit

Generally, a battery is charged with a small amount of AC or DC voltage. If we want to charge the battery with an AC source,  we need to first limit the large AC voltage, need to filter the AC voltage to remove the noise – regulate and get the constant voltage and then give the resulting voltage to the battery for charging. Once charging is completed the circuit should automatically be turned off..

The AC voltage is given to the step-down transformer to step down the voltage to 20V approx. This voltage is given to the SCR for the rectification of the voltage. The rectified voltage is used to charge the battery. The battery attached to the charging circuit doesn’t completely get dead and get discharged. This gives forward bias voltage to the transistor, resistor R7 and diode D2 which get switched on. When the transistor is switched on, the SCR switches OFF.
When the voltage of the battery is dropped, the transistor gets switched off; the resistor R3 and diode D1 get the current to the gate of the SCR automatically; this triggers the SCR and it conducts. The AC input rectifies the input voltage and give it to the battery via R6 resistor. This charges the battery; when the voltage drop in the battery decreases, the forward bias current also gets increased to the resistor. When the battery is fully charged, the Q1 transistor turns on and off the SCR.

#### Water Level Indicator

The water level indicator project is used to display the information about the level of the water tank by using LED lights. This project mainly uses IC CD4066 and the circuit diagram of water level indicator is shown below. This circuit is built with four LEDs. When the water level is at ¼ of the tank, then LED1 glows. When the water level is ½ of the tank, then LED2 glows. When the water level is at ¾ of the tank or the water level is full, then the LED4 glows.

#### Super Bright LED Flasher

This super-bright LED flasher circuit uses a single driver transistor, which takes its flash rate from a flashing LED. The flash light cannot be changed by the brightness of the white LED. This  LED can be adjusted by changing the resistor 1K across the 100u electrolytic to 10k.The 1K resistor discharges the 100u. So that when the transistor turns ON, the charging current into the 100u illuminates the white LED. If a 10k discharge resistor is used, the 100u is not fully charged and the LED doesn’t flash as bright. All the parts in the photo are in the same place as shown in the circuit diagram, thus make it easy for us to see how the parts are connected.

#### Fridge Door Alarm

The fridge door alarm circuit bounded in a small box must be placed in the fridge close to the lamp. When the fridge door is closed, the inside of the fridge gets dark, the photo resistor R2 presents a high resistance (>200K). Thus, clamping IC1 by holding C1 fully charges across R1 & D1. When a light beam enters from the opening, the photo resistor presents a low resistance (<2K). So, IC1 wired as an astable multivibrator, starts oscillating at a very low frequency; and, after a period of about 24 seconds, its o/p pin goes high. The IC2 chip is also wired as an astable multivibrator, driving the Piezo sounder irregular at about five times/second. The alarm is activated for about 17 seconds, and then stopped for the same time period and the cycle repeats until the fridge door closes.

#### 100 Watt Inverter Circuit

Here, a 100 Watt inverter circuit is built by using minimum number of components. This circuit uses the CD 4047 IC and 2N3055 transistor. The IC generates 100Hz pulses and transistor for driving the load
The IC1 CD 4047 wired as an astable multivibrator produces two 180 degrees out of phase 100Hz pulse trains. These pulse trains are pre amplified by the two TIP122 transistors. The o/p of these transistors is amplified by four 2N 3055 transistors. For each half cycle, two transistors are used to drive the inverter transformer.

At the secondary of the transformer, the 220V AC will be available. This circuit works great for small loads like few bulbs, fans, etc. This inverter is best for who needs a low cost inverter at the region of 100W

This is all about a few simple electrical mini projects with circuit diagrams for all those individuals who are interested in building their own electrical mini project circuits. We hope this type of electrical engineering project ideas will be helpful to the students.Furthermore,for any queries regarding this article or electronics projects, eee mini projects with circuit diagram please do give your comments, feedback and suggestions in the comment section below.

Photo Credits:

1. Sumon EEEcareer says:

Hello Tarun Agarwal,

Thanks a lot. It’s very easy and simple project. I have done “Water Level Indicator” project for my college. My Faculty is very happy to see my project. My family members are also happy to see that, Thanks again dear.

1. Tarun Agarwal says:

Hi Sumon
Thank you for taking the time to give your feedback

2. S.MUTHUMALA PANDIAN says:

can u give still simple project……….

1. Jitu das says:

2. Tarun Agarwal says:

Hi Jitu
I sincerely appreciate your kind response regarding my article
For more details please contact to Sathish on +91 8885507011 or you can email us on info@edgefxkits.in

3. Viknapriya says:

Hi glad 2 see these simple projects but I need little innovative projects for first year level engineering projects exhibition

4. mahend says:

sir i want diffrent type of projects

1. Tarun Agarwal says:

Hi Mahend
Please go through the below link so you can find the different types of categories
https://www.edgefxkits.com/

5. fausto garcia says:

nice ideas

1. Tarun Agarwal says:

Hi Fausto Garcia, Thank you for your appreciation. Also, please check the user friendly website http://www.efxkits.com for project ideas on all the latest technologies. Please check the website for complete details in the kit content section: http://www.efxkits.com/kitdetails/ and go through the FAQ: http://www.efxkits.com/contact-us/#faq for details. Further if you have any queries you can mail us at info@edgefxkits.in or please call on +91 9908778000 for clarifications/personal counseling. Raji (Contact India: +919959178000, Contact International: +1 201 44 83073)

6. vijay says:

hi sir,i want some innovative projects

7. siva says:

sir i need bulk EEE projects pls contact

1. Tarun Agarwal says:

Hi Siva, Please follow the link: https://www.edgefxkits.com/electrical-projects/ for all the Electrical based latest projects. Please check the user friendly website http://www.edgefxkits.comfor complete details in the kit content section: https://www.edgefxkits.com/kitdetails/ and go through the FAQ: https://www.edgefxkits.com/contact-us/#faq for details. Also, go through the link: https://www.edgefxkits.com/marketinformation/#aboutBulkorders for details on bulk orders. Further if you have any queries you can mail us at info@edgefxkits.in or please contact Mr. Mahesh on +91 9949518885 for clarifications/personal counseling on the process of Bulk Orders. Raji (Mobile: +91 9959178000)

8. g.murali says:

i have idea for project so i want how to implement that

1. Tarun Agarwal says:

Hi Murali,

Please check the user friendly website http://www.edgefxkits.com for project ideas on all the latest technologies. Please check the user friendly website for complete details in the kit content section and go through the FAQ for details. Further if you have any queries you can mail us at info@edgefxkits.in or please call on the toll free no. 1800 108 7475 for clarifications/personal counseling.

Raji (Mobile: +91 9959178000)