Get Ready to Build 10 Different Electronic Projects on Your Own!

This article is for all those electronics enthusiasts eager to fidget with the basic components in electronics, available all around. So here are 10 very simple yet interesting electronic projects.

1. Crystal Tester

Crystal is used as an oscillator, to generate a high frequency. In all the major electronic projects crystal is used instead of coil. It is easy to test a coil using a multimeter but it is quite tough to test a crystal. So in order to overcome this problem this simple project is designed using few passive components for testing the crystal.


Circuit Components 

Circuit Components Table 1Circuit Connection

This electronic circuit consists of a crystal oscillator, two capacitors and a transistor forming a Colpitt oscillator. A combination of diodes and capacitors are used for rectification and filtering respectively. Another NPN transistor is used as a switch to make the LED glow.


Circuit Diagram 
Crystal Tester Circuit Diagram
Crystal Tester Circuit Diagram

Circuit Operation

The entire circuit is operated with two transistors, two diodes, and few passive components. If the testing crystal is good then it operates as an oscillator in combination with transistor. The diode rectifies the output of the oscillator and the capacitor filters the output. This output is now fed to the base of the transistor and the transistor starts conducting.

An LED is connected to the collector of the transistor through the resistor. The LED gets proper biasing and starts emitting light, i.e. it starts glowing. In case if any fault occurring in the testing crystal then the LED does not glow.

2. Battery Voltage Monitor

This electronic project is used to monitor the charging and discharging of the battery such that the battery voltage doesn’t exceed the specific level of that battery. It basically acts as a controlled battery charger. It indicates the state of the battery.


Circuit Components 

Circuit Components Table 2Circuit Connections

The circuit of the battery voltage monitor is implemented using an operational amplifier IC (LM709) which is used as a comparator. Here a bi color LED is used to indicate the status of the battery. A combination of a resistor and a potentiometer is used as a potential divider.

The voltage at this potential divider is fed to the inverting input pin of the comparator. The resistor R3 and R4 is used as current limiter of the LED.


Circuit Diagram
Battery Voltage Monitor Circuit Diagram
Battery Voltage Monitor Circuit Diagram

Circuit Operation

The entire electronic circuit is powered by 12V battery. When the voltage level of the battery increases up to 13.5 volts, the voltage at the inverting input is less than then voltage at the non inverting input and the output of the OPAMP goes low. LED1 begins to emit red light which indicates that battery is over charged.

When the voltage level of the battery falls to 10volts, the voltage at the inverting terminal is less than the voltage at the non inverting terminal. The OPAMP output goes high. LED2 begins to emit GREEN light which indicates that the battery needs to be charged.

3. LED Indicator Light

This project is used to design an indicator using LEDs. It is an inexpensive electronic project and can replace the traditional indicators used in bikes and cars.


Circuit Components

Circuit Components Table 3Circuit Connection

A 555 timer is used in astable mode to generate clock pulses. The trigger pin of the timer is shorted to the threshold pin. A BCD counter IC 7490 is used to indicate the pulse count by switching on/off the LEDs. The LEDs are connected to the output of the counter IC.

Circuit Diagram
LED Indicator Light Circuit Diagram
LED Indicator Light Circuit Diagram

Circuit Operation

The pulses generated by the 555 timer are fed to the clock input of the counter. The counter accordingly generates a high signal at each of its output pins based on the number of the pulses received. For a high signal at any output pin, the connected LED glows. When the counter starts progressing, the light appears to move towards left.

If the frequency of the pulses increases, then the light emitted by the LEDs appears to move in one particular direction. If the frequency is high then the LED’s appears to glow at an instant. Individual flicker is eliminated as the light appears to move left at a faster rate.

4. Electronic Thermometer

This is one of the simple electronic projects where an electronic thermometer is designed. It can be used for measuring wide range of temperature. This thermometer can replace the clinical thermometer used by doctors.

Circuit Components Table 4Circuit Connection

A 9V battery is used as the DC power supply source for the entire circuit. A diode is used as a temperature sensor and is connected in feedback path of an operational amplifier. The input voltage is fixed by VR1, R1, and R2 at the non inverting pin 3 of the op-amp IC1. The output from this IC1 is fed to the inverting terminal of another OPAMP IC2. The non inverting terminal of this OPAMP is given a fixed voltage signal. The output from this IC is connected to an ammeter which shows the current reading which is calibrated to show temperature.


Circuit Diagram
Electronic Thermometer Circuit Diagram
Electronic Thermometer Circuit Diagram

Circuit Operation

The voltage drop across the diode changes with change in temperature. At room temperature, the voltage drop across the diode is 0.7V and reduces at the rate of 2mV/degree Celsius. This voltage change is sensed by the operational amplifier. The output of the operation depends upon the voltage drop across the diode.

Here another Operational amplifier is used as voltage amplifier. The output from IC1 is amplified by the operational amplifier IC2. The ammeter indicates the current amplitude of the output signal and this is calibrated to indicate the value of the temperature.

5. Electronic Motor Controller

This electronic circuit is designed for controlling the motor using electronic devices. It is more efficient than any electromechanically controlling device. This project is also designed to eliminate the problems of noise triggering and noise pulses. These types of electronic projects are very simple and easy to be constructed and implemented. Here, we have demonstrated lamp intensity control instead of motor control.


Circuit Components

Circuit Components Table 5Circuit Connections

The secondary of the transformer is connected to the diodes. The diode D1 and D2 are used for rectification and the capacitor is used as noise filter of the switching circuit. Here 5 transistors are biased in common emitter mode. The transistors Q1, Q2, Q3 are used to detect any fluctuations in voltage. The output of transistor Q1 is given to transistor Q2. The output from transistor Q2 is given to the base of transistor Q3 and the output from transistor Q4 is fed to the base of transistor Q4. The collector of transistor Q5 is connected to a relay.

Here a 2 CO relay is used. A reverse biased diode is also connected to the relay (at its other point). The resistor network R11, R12, VR1 forms a current sensor circuit.

Circuit Diagram
Electronic Motor Control Circuit Diagram
Electronic Motor Control Circuit Diagram

Circuit Operation

The entire circuit is power by pressing the switch SW1. When the switch sw1 is pressed the transformer gets mains voltage supply and converts it into low voltage. The current through the resistor R8 gives base current to the transistor T5.

When the relay gets activated the motors also switches on. The current sensor senses the logic high signal. When the transistor T4 receives a logic high signal from the current sensor, the R8 resistor gives low signal to the transistor T5 and the transistor will not conduct.

As a result the relay does not get energized and the motor is switched off. SW2 switch is used to switch off the motor. The transistor T4 gets on when the over and under voltage is given to the T3 transistor. The capacitor C2 and R10 resistor together forms a low pass filter for avoiding noise triggering and pulses. It also provides sufficient time delay to the circuit.

6. Electronic Dice

A dice is a cube which is often used in many indoor games. Clearly a dice needs to be unbiased. Conventional dices used often get biased due to certain deformations or any defects in the construction. Here in this electronic project, an electronic dice is built which will always remain unbiased and would provide accurate reading.


Circuit Components

Circuit Components Table 6Circuit Connection

Here a 555 timer is connected in astable mode. A resistor of 100K is connected between pins 7 and8. A resistor of 100K is connected between pins 7 and 6. The output from the timer at pin 3 is connected to the clock input pin of the counter IC 4017.
The enable pin of the counter IC is grounded.  4 output pins (Q0 to Q5) are each connected to an LED. The 5th output pin is connected to the reset pin 15 of the counter IC. This whole circuit is powered by a 9V supply.


Circuit Diagram
Electronic Dice Circuit Diagram
Electronic Dice Circuit Diagram

Circuit Operation

With proper values of the resistor and capacitor, the 555 timer generates clock pulses at a frequency of 4.8 KHz, i.e. a clock cycle of quite low time period. When these pulses are fed to the counter, each output pin goes high according to the number of pulses. The LED connected to each pin starts glowing as the pin goes high. In other words the LEDs start glowing for each corresponding count. The switching of the LEDs is at such a fast rate that it cannot be perceived by human eye. The counter resets automatically as the count advances to 7.

7. Automatic car head lights turn OFF Circuit

This electronic circuit saves the battery energy while the car ignition switch is turned OFF. It reduces the need for checking whether the head lights are ON/OFF. We can also vary the time for turn OFF the lamps by the varying the potentiometer connected to the timer IC.


Circuit Components

Circuit Components Table 7Circuit Connection

This circuit mainly comprises of 555 timer IC, NPN transistor and the relay. Timer IC is connected in the mono stable mode of operation. In this mode timer requires a trigger input to generate the pulse with a certain time period. Output from the timer IC is connected to an NPN transistor. The collector of this transistor is connected to one terminal of a relay coil. Relay is used to control ON/OFF periods of the lamp.


Circuit Diagram
Automatic Car Headlights Circuit Diagram
Automatic Car Headlights Circuit Diagram

Circuit Operation

An ignition switch acts as a triggering pulse to the timer. When the ignition is switched ON, a high logic signal is fed to the trigger pin of the timer and the timer doesn’t produce any output. The diode as well as the transistor doesn’t conduct. The relay coil gets energized as it is connected to proper supply and headlights get switched on. When the ignition switch is turned OFF, a low logic pulse is given to the second pin of the timer so the output of the timer goes HIGH for time period which is set by the RC values. The relay coil will be energized and the lamp will glow, but for a certain minimum time period and then will be switched off.

8. Fire Alarm Circuit

This simple electronic circuit is designed to give an alarm incase when fire breaks out. This circuit works on the principle that ambient temperature increases as fire breaks out and this temperature changed is sensed and processed to give an alarm signal.


Circuit Components

Circuit Components Table 8Circuit Connection

Here a PNP transistor is used as a fire sensor and its collector is connected to the base of a NPN transistor through a series combination of a potentiometer and a resistor. The emitter of this NPN transistor is connected to the base of another transistor. The emitter of this transistor is connected to a relay. A diode is connected across the relay for back EMF protection. This relay is used to control the switching of the load, which can be a horn or a bell.


Circuit Diagram
Fire Alarm Circuit Diagram
Fire Alarm Circuit Diagram

Circuit Operation

When fire breaks out, the temperature increases. This causes the leakage current of the PNP transistor Q1 to increase. As a result transistor Q2 will be biased and starts conducting. This in turn brings transistor Q3 to conduction. The collector and emitter terminals of this transistor are shorted and current flows from the DC power supply to the relay coil. The relay coil gets energized and the load gets switched on.

9. Mobile Incoming Call Indicator

This circuit is designed to give an indication for incoming call on a cell phone. This electronic project proves to be a relief from the nuisance created due to the sudden ringing of the mobile. There are many situations where we cannot switch off the mobile nor put it in silent mode, yet a loud ring can prove to be very embarrassing. This circuit proves to be a relief in such situations.


Circuit Components

Circuit Components Table 9Circuit Connection

A coil is connected with a capacitor to the base of an NPN transistor. The collector of this NPN transistor is connected to the trigger pin of the timer IC555. This timer IC is connected in mono stable mode with a resistor of 1M connected between pins 7 and 8. The output of the timer at pin 3 is connected to the anode of the LED and the cathode of the diode. This whole circuit is powered by a 9V battery.


Circuit Diagram
Mobile Incoming Call Indicator Circuit Diagram
Mobile Incoming Call Indicator Circuit Diagram

Circuit Operation

When the mobile receives an incoming call, its transmitter generates a signal around 900MHZ.  This oscillation is picked up by the coil in the circuit. As current flows from the coil to the base of the transistor, it conducts. As the transistor conducts, i.e. gets switched on, the collector and emitter are shorted and connected to ground. This gives a low logic signal to the trigger pin of the timer and the timer is triggered. A high logic signal is produced at the output of the timer. The LED gets proper biasing and starts blinking. This blinking of the LED indicates the incoming call.

10. LED Knight Rider Circuit

LED Knight rider running circuit is a light chaser or running light effect generator which produces forward and reverse moving effects. This type of lighting is used mainly in the automotive applications and other sequential type of lighting applications. It is one of the application circuits of IC 4017.

Circuit Components

Circuit Components Table 10Circuit Connection

This circuit comprises of two IC’s i.e., timer IC and decade counter IC. 555 timer IC generates the clock pulses which are fed to the clock signal of the decade counter IC. The rate at which the lights are glowing depends on the RC time constant or clock frequency of the timer. Decade counter IC 4017 has ten outputs which go on high in sequence when pulses are applied at the clock input. These LED’s are connected through the diodes to produce the to and fro chasing.


Circuit Diagram
LED Indicator light Circuit Diagram
LED Indicator light Circuit Diagram

Circuit Operation

555 timer IC is connected in astable mode so that it will continue to generate the pulses at a rate fixed by the RC values connected to it. These pulses are applied to the 4017 IC so the outputs of this IC are sequentially tuned ON at rate fixed by the timer. Initially the LEDs are switched on in increasing order and as the last LED gets switched on, the switching of the LEDs occur in reverse order.

In other words, the first 6 outputs are connected directly to the LEDs to produce sequential switching of the LEDs and the next 4 outputs are connected to each LED so as to produce a reverse lighting effect. By varying the potentiometer at the timer we can get the variable rate of the LED’s switching.
So simple and basic circuits, isn’t it? Don’t you find all these electronic projects worth to be implemented at your home or used as ? Of course, I guess. So there is this one little task for you. Amongst all these projects, pick up one which catches your attention and try to make some changes in it.

Post these changes as well as your observations in the comment section below.


please follow the below link: 5 in 1 solderless project
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Hi, I`m Sostenes, Electrical Technician and PLC`S Programmer.
Everyday I`m exploring the world of Electrical to find better solution for Automation. I believe everyday can become a Electrician with the right learning materials.
My goal with BLOG is to help you learn Electrical.
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