This article discusses about some simple electronic circuits for beginners, which can be used in electronic circuits. These electronic circuits are used for simple electronic circuits projects, beginners, hobbyists and engineering students. The following simple circuits can be used as a mini project in engineering. But these circuits are not apt for final year projects. The following circuit comes under the category of the small, hobby, etc. These simple circuits are very essential for main projects. Because, major projects are designed with several combinations of electronic circuits.
Simple Electronic Circuits for Engineering Students
The simple electronic circuits are very useful in getting an idea about the basic circuits used in the electronic projects. These simple circuits are explained in detail along with neat circuit diagrams.
Simple Touch Sensitive Switch Circuit
The circuit diagram of a touch sensitive switch is shown below and it is used almost in all electronic circuits. The circuit of the sensitive touch switch uses IC 555.It is arranged in the mode of monostable multivibrator. In monostable mode, the output of the IC 555 triggers by producing a high logic in response to an active at its input of the pin2. The output activation time period depends on the values of capacitor C1 and variable resistor VR1.
Whenever the touch plate is touched, then the pin2 is dragged to a lower logic potential which may be <1/3 of Vcc. This promptly returns the o/p situation from low to high to triggering the connected relay driver stage. When the capacitor C1 gets discharged, then the load turns ON. Here loads are connected to the relay contacts
Electronic eye or magic eye is used as an automatic guest indicator on the bottom of the door entrance. Once an electronic eye is installed on the door there is no necessary to install a call bell. The applications of call bell are used as a burglar alarm for home, banks, etc. When the light dependent resistor is attached to the door, someone tries to open the door, a shadow of that person will fall on the light dependent resistor. Then, the circuit gets triggered and gives a sound through the buzzer.
The circuit of an electronic eye is built with a NOT gate from CMOS IC D4049, This IC includes six independent NOT gates in one package but used only one NOT gate. When the output of the NOT gate is high and i/p of the pin3 is lower than the 1/3rd level of the supply voltage. When the supply voltage level is above of 1/3rd then the o/p goes low. The o/p has only two states 1 and 0 and cannot continue in any middle stage. The circuit is powered by a 9 volt battery for handy use. In this circuit, pin1 is connected to +v supply where pin8 is connected to GND terminal. The main function of an LDR is used to sense the presence of an object and the value of the LDR depends on the brightness of the light falling on it.
A potential divider circuit is made with 220 KO resistance and LDR connected in series.When the light depending resistor is getting low voltage in darkness and light, then more voltage we can get from the voltage divider.This divided voltage is given to the i/p of the NOT gate. As soon as a light dependent resistor gets dark and the NOT gate i/p voltage falls 1/3rd of the voltage and pin-2 gets high. Finally the buzzer which is connected to the o/p gets triggered.
Air Flow Detector Circuit
The circuit of the air flow detector is used to check the rate of the flow of air and give a visual indication, and used to check the given space whether there is flow of air is not. This circuit is built with an incandescent bulb works as a sensing part. When there is no flow of air, then the resistance of the filament is low. In the same way when there is air flow, then the resistance drops. Because the flow of air will eliminate the heat which is produced by the filament.This difference in the resistance will generate different voltages across the filament in the bulb. These differences will be received by the LM339 op-amp. The illumination of the LED at its o/p will be changed proportionally to the flow of air.
UPC1651 based FM TX
The circuit diagram of the PC Based FM transmitter is shown below. This circuit uses a ICUPC1651.This IC is a wide band silicon amplifier and it has a wide range of power gain(19dB)and frequency response(1200MHz). This IC can be worked with 5V DC. The audio signals which are received from the microphone are fed to the input in2 of the IC through the C1 capacitor.Here, in this circuit ‘C1’ capacitor acts as a noise filter.
The FM modulated signal will be accessible at the o/p pin4 of the IC. Here, capacitor ‘C3’ and Inductor ‘L1’ forms the necessary LC circuit for making the oscillations. The frequency of the TX can be changed by regulating the C3 capacitor.
Flashing Lamps Using 555 Timer
The circuit of the flashing lamps using 555 timer is shown below.Here, IC 555 timer works as an oscillator and it generates pulses at a max of 10mins. The frequency of this time interval can be altered by using VR connected between the two pins like VCC and discharge pin. The value of the other resistor set to 1K, and the capacitor between the pins 1&6 are set to 1uF.
The o/p pin of the 555 timer is connected to the relay and a diode which are connected in parallel.The following circuit uses four lamps, two of them are connected in series and remaining two are connected in parallel. These lamps can be controlled by using a DPST switch.
This is all about a few simple electronic circuits for engineering students who are fascinated in designing their simple electronic projects. We hope this kind of circuits will be helpful for beginners and the engineering students, Furthermore, any doubts regarding electronics projects for beginners, please give your feedback by commenting in the comment section below.