To understand the tank circuit operation, consider the capacitor is already charged from a DC source with polarity as shown in the below figure. Here the upper plate is positive terminal with respect to lower plate. It means there is a voltage across the capacitor and it has electrostatic energy. When the switch SW is closed, the capacitor will start to discharge the stored energy through inductor.
The current flow is indicated in the below figure. So the capacitor will get charge in opposite polarity. Once the collapsing magnetic field has recharged the capacitor, the capacitor starts to discharge. This time the current will flow in opposite direction as shown in the below figure. The sequence of charge and discharge creates the alternating motion of electrons or an oscillating current. The energy is alternately stored in electrostatic field of capacitor and the electromagnetic field of the inductor.
The frequency of oscillations in the tank circuit is decided by the values of C and L. It is given by. How to control Speed of DC series Motor? How Calling Bell Works? How to use Bridge Rectifier IC? How to identify Terminals? Thanks for reading about How Tank Circuit works?
A capacitor is an electrical component and it has two conductive plates. These plates are divided with a nonconductive material like wax paper. Whenever the capacitor gets an electric charge, then two charges like positive as well as negative to collect on conflicting ends of the non-conductive face. Because opposite charges cannot flow through the surface but it attracts. The charges will supply to the inductor coil through the connecting wires to charge the inductor in electromagnetically.
The circuit diagram of the tank circuit is shown below. The circuit can be built using electrical and electronic components like an inductor and capacitor. The values of these components are a ceramic capacitor 1nF and an inductor mH. Now if we removed the power source, the capacitor starts discharging through the inductor.
Now inductor starts storing energy in form of a magnetic field. Once the voltage across the inductor is raised than the voltage across the capacitor, again inductor starts to dissipate the energy and provides energy to the capacitor to charged up in opposite polarity. When the capacitor gets fully charged by the energy supplied by the inductor, it again starts discharging through the inductor.
This whole process continuously repeated until the whole energy dissipated by the resistance of the circuit. Now, we will discuss each part of the waveform of the oscillating signal produced by the LC Tank Circuit which will help you to a better understanding of the working of Tank Circuit.
Here you can see the waveform in the below figure. First of all, if you observed the overall waveform, you will notice the magnitude of the waveform gradually decreased, it is because energy gradually dissipated through the internal resistance of the circuit, and at a time energy will fully dissipate then again we need to charge the circuit by an external power source.
The rising portion of the first half cycle indicates the charging of the capacitor by the external power supply and the peak point indicates, capacitor fully charged at the supply voltage level.
When we remove the power supply from the circuit, the capacitor will start discharging through the inductor which indicated by the decreasing portion of the first half cycle of the waveform, and the zero point indicates that the capacitor fully discharged. The rising portion of the negative half cycle indicates that the capacitor again starts charging in opposite polarity taking energy from the inductor and the decreasing portion indicates that the capacitor discharges.
Next all cycles indicate the continuous repeating of the whole process until the full energy is dissipated. To build a Tank circuit we required only two components, inductor, and capacitor. Just connecting them in parallel we will able to make an LC tank circuit. To start the work of that circuit, first, we must charge the circuit by an external DC power supply. In that LC Tank circuit, we can modify two parameters, one is the amplitude of the signal and another one is the frequency of the signal.
We can change the amplitude of the signal by changing the voltage level of the external dc power supply. To change the frequency of the signal we need to change the value of the inductor and capacitor.
So we need the proper selection of inductor and capacitor to get the desired frequency. Remember that always non-polarised capacitor or ceramic capacitor is used to make the tank circuit. If we required high frequency, then we need to take a lower value of capacitor and inductor because low-value capacitor provides very fastly charging and discharging property, so the time period will be less, so here we can get the high frequency.
If we required low frequency, then we need to take a high-value capacitor and inductor because a high-value capacitor takes more time to charge and discharge, so the time period will be more, so here we can get the low frequency.
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