RLC Series Resonant Frequency Calculator

When a capacitor, resistor and inductor are connected in series, a series resonant circuit is formed. A series resonant circuit has a frequency response that has a minimum reactance and maximum gain at the resonant frequency. The series resonant circuit effectively acts as a bandpass filter.


The resonance frequency for a series resonant circult can be calculated with the formula:

fr = 1/2*PI*SQR(LC)

Where

Fr = Resonant Frequency in Hertz
PI = 3.14
L = Inductance in Henries
C = Capacitance in Farads

The formula can be derived by equating the inductive reactance to the capacitive reactance in a series circuit and then solving for the frequency.



Series Resonance Frequency Calculator

To calculate the resonance frequency, you can use the calculator below. For the calculator, enter in the inductance and capacitance. The resulting resonant frequency is then calculated. You can also use the up and down arrow keys to change the values of inductance and capacitance and compute the resonant frequency in real time. For calculating the resonant frequency, the resistor value is not needed. The resonant frequency is only dependent on the inductance and the capacitance.

RLC Series Resonance Calculator

Inductance Henries Millihenries Microhenries Nanohenries
Capacitance Farads miliFarads microFarads nanoFarads picoFarads
Series Resonance Frequency :

Hertz KiloHertz MegaHertz GigaaHertz

Capacitors in Parallel: Electronics Tutorial # 7

When capacitors are placed in parallel, capacitors add. The equivalent capacitance of capacitors in parallel can be calculated from the formula:

Equation 1: Ceq = C1 + C2 + C3 + C4 + ..... + CN

For the circuit below, the equivalent capacitance is calculated  with equation  1 as" 

Ceq = 1uF + 2uF + 2uF + 3uF = 8uF 

Add Capacitors in Parallel to Obtain the Equivalent Capacitance

Capacitors are measured in units of Farads. A uF or microFarad, is one millionth of a Farad. For the above example, the equivalent capacitance is 8 microFarads.  

Applications 

Capacitors are often placed in parallel to increase the capacitance to a specific value that is not available as a standard component. In DC power supply application, smaller capacitors are put in parallel because smaller capacitors will filter out ripple better than one large equivalent capacitor. Parallel capacitors are often used in Kinetic Energy Conversion systems (used in electric cars). 

Limits 

Capacitors can be placed in parallel, but in practice, the total amount of voltage that can be applied across capacitor in parallel can not exceed the lowest capacitor voltage rating of the capacitors within the parallel bank. 

Learning Links 

Bookmark Tutoring.com

Capacitors in Parallel

Resistors in Series: BookMark Electronics Tutorial #6

Placing resistors in series allows you to create higher resistance values. And thats because resistors in series add. Resistors in series have the same current flowing through them. The equation for resistors in series is

                                         Equation 1 Req = R1 + R2 + R3 + ...... + Rn

For the example below, there are four resistors in series. The equivalent resistance is equal to the sum of the resistors: Req = 100 + 200 + 300 + 200 = 800 Ohms

For more information visit www.bookmarktutoring.com

Electronics Tutorial #4: Ohms Law

If you want to build your own electronic circuits, one law you must learn and know how to use is Ohms law. Ohms law lets you calculate the current and voltage through and across a resistor. The basic equation that Ohms law states is that voltage is equal to the product of current and resistance. In equation form:

Equation 1: V= IR

If you know the voltage across a resistor and the current through a resistor you can compute the value of the resistor. Similarly, if you know the resistor value and the current through the resistor you can compute the voltage across the resistor.  For example if you put 2 Volts across a 1 Ohm resistor, from Ohms law you calculate that the current is 1 Ampere.

If you don't want to do the hand calculations required for Ohms law, you can always use a circuit simulator. The LTSpice circuit simulator, is a free simulator, that you can use to calculate the voltage across and the current through a resistor. In the LTSpice circuit schematic below, a 10 Volt battery is placed across a 1000 Ohm resistor. Using Ohms law, you can calculate that the current through the resistors would be 0.01 Ampere or 10 mA. A mA (milliamp) is 1/1000th of an Ampere.

LTSPICE Ohms Law Circuit Simulation

There are many advantages of using the LTSpice circuit simulator to analyze a circuit. One advantage is that it eliminates calculation errors. The second advantage is that you can analyze complex circuits, that would take hours of hand calculations, in seconds.  The third advantage is that it facilitates learning and allows you to build intuition about circuit design.

For more information visit www.bookmarktutoring.com

Learning Links

LTSPICE Download

Electronics Tutorial: Diode Connected JFET for Overvoltage Protection Applications

If you need to protect sensitive circuits from overvoltage breakdown conditions, diodes are one way. When the input voltage becomes to high, the diode will conduct and limit the voltage to around 0.7 volt. However, if your circuit is used to measure low-level currents, even a slightly biased diode can siphon off a significant amount of current - seriously degrading measurement accuracy

In order to keep your measurements accurate and protect your measurement circuitry you will need a diode that has a very low current in the non conduction region (below the forward bias voltage). In this case, a JFET connected diode is an alternative. When a JFET is connected as a diode, it exhibits very low levels of leakage current in the non-conduction region.

A JFET connected diode is simple to build. Just connect the source and the drain of an N-Channel JFET together. The gate of the JFET will serve as the cathode and the drain/source will be the anode. Such a connection is shown in the LTSpice schematic below. For this circuit, a 1 Volt sine wave (at 300 Hz) is applied to the JFET diode.

A diode can be easily constructed with an N-Channel JFET

The output of the JFET diode is taken across the load resistor, R1, Just like a regular diode, it will clip the negative portion of a sine wave. Also just like a regular diode, it will not conduct until the driving voltage reaches 0.7 volt. This shortens the duty cycle of the output waveform and lowers the peak voltage of the output waveform. 

The JFET diode clips the negative cycle of a sine wave

For more information visit www.bookmarktutoring.com

LEARNING LINKS

Diode Connected JFET Protects Op Amps
Common Circuit Applications (JFET Diode)