# Calculating the frequency based on LC circuit

by guns
Tags: based, circuit, frequency
 P: 4 Hi all, I am currently building up a lightning detector based on this website: http://www.techlib.com/electronics/lightningnew.htm as the diagrams shows, the resonance tank included a 10mH inductor and a 10pF capacitor. As I want to calculate the resonant frequency (using the formula f = 1/2pi*sqrt(LC)), the answer was 5Hz, which is far from the desired range (should be around 200kHz) is there any mistake in my calculation or concept? Thanks for your help. Guns
 Mentor P: 10,853 How did you get your answer? Did you consider the SI prefixes (milli, pico)? I think there are brackets missing in your equation.
 P: 4 mfb, I did it this way: 1/2pi*sqrt(10^(-3)*10^(-12)) which approxmately equals to 5 Hz.
P: 427

## Calculating the frequency based on LC circuit

Following up on mfb's post, you're missing brackets and are using the wrong values for the SI units:

10 mH = 10*10^(-3) H
10 pF = 10*10^(-12) F

1/(2*pi*sqrt(10*10^(-3)*10*10^(-12))) Hz = 503.3*10^3 Hz = 503.3 kHz
 P: 4 oh my, silly me. Thanks mfb and milesyoung!

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