Calculating Self-Resonant Frequency of 6mm 30-Turn Inductor Without Parasitic Capacitance

hi
i need to find my self inductance resonant frequency
my inductor has 6 mm diameter 30 turns and 1 mm length
as i dont know my parasit capacity how can i calculate my sekf resonant frequency.
can anyone help me
thank you

Hi Vedat,

I think we need more information to get the resonant frequency. First, from your inductor, you stated that it has 6mm diameter, 30 turns, 1mm length, what is the inside diameter of the coil if Im assuming right that this is a coil type? There are different types of inductors, so kindly clarify this part. Second, to get the self resonant frequency, we need to have information about capacitance. Kindly check on this. Furthermore, there are free online calculators to solve for your inductance, capacitance and even self resonant frequency.

http://www.eeweb.com/toolbox/wire-inductance
http://www.1728.org/resfreq.htm
http://www.microwaves101.com/encyclopedias/inductor-mathematics

Hope this helps,
Kevin

I think the best way will be: build simple LC Oscillator and measure resonance frequency. Or connect it to generator through resistor and measure voltage and phase shift between input and coil voltage. Increasing frequency find highest voltage at coil terminal. Highest voltage indicates resonant frequency. I assume it will be parallel resonance between parasitic capacitance and inductance. At resonance frequency we have only resistance (no reactance) and if you have high Q you will get very high resistance L/(R*C), thats why you should get high voltage at sekf

Hi Kevin and Tomasz
firstly thank you very much indeed for responding me.
the inside diameter of the coil is 6 mm and wire diameter is 0.1 mm. and yes it is a coli.
i did check the coil in the LC oscillator and my resonant frequency is 7.26 MHz. the problem is that i want to know how can i calculate my resonant frequency without using LC oscilloscope.
kind regards

Ok, my mistake . In this matter it depends on how you wind your coil. More layers more capacitance but it is quite complicated. Simple method is to imagine that two layer coil act as a parallel plate capacitor. I've multiply capacitance by 0.25 because this hypothetical capacitor has not uniform surface.
C = 0.25 *(Er*Eo*A)/h
h-thickness of coil
Er Eo permitivity
A surface area.
For single layer coil i assume 0 capacitance.