# lc circuit

Discussion in 'Wireless & RF Design' started by Lightfire, Mar 1, 2012.

1. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
ok.

im just wondering if the values of capacitor and inductors must be the same. or the inductor must have greater value than capacitor.

coz it says that capacitor charge came zero after it transfer it to the inductor.

thnx

2. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
It has to do with reactance. Capacitors and inductors resist the flow of AC electricity similar (well, no too similar) the way a resistor slows the flow of DC electricity.

As the frequency changes, so does the reactance (which is similar to ohms). The frequency where the reactance of AC for both the coil and the capacitor is the resonant frequency.

If you really want to understand the concepts you are going to have to read. There is no other way to learn this stuff. You can ask more informed question as you go, but this site has a text book attached.

3. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
is the standard unit for LC circuit ---

pf for cap and nh for ind

ok

1/2π√(240,000nh x 384pf)

meaning 60,318.58hz? what??

thnx

4. ### debjit625 Well-Known Member

Apr 17, 2010
790
186
For AC any LC circuit will offer some reactance (opposition to current change),and its measured in ohms like resistance.In real life any LC circuit will also offer some resistance with the reactance.And the combination of this resistance and reactance is called impedance,its also measured in ohms.

Good Luck

5. ### debjit625 Well-Known Member

Apr 17, 2010
790
186
Its the formula to find out the resonant frequency of a LC tank circuit.
$f = {1\over {2\pi \sqrt{LC}}}$
The values for inductance L is in Henries ,Capacitor C in Farads and frequency in Hertz.

You cant put nano henrys and pico farads in the equation...you have to convert them to henry and farad before you plug them into the equation.
384 pf = 384 /1000000000000 = 0.000000000384 farads
240,000 nh = 240000 / 1000000000 = 0.00024 henries

That gives around 524529Hz

Good Luck

Last edited: Mar 3, 2012