# Understanding Working of LC Meter

I am trying to understand working principle of the circuit given in the link below :

http://kripton2035.free.fr/Resources/lcmetersch.pdf

I realized that the circuit is basically relaxation oscillator with LC tank circuit attached to its non-inverting input. I know that when the output of the comparator becomes HIGH (5V) capacitor in the negative feedback path charges and and after reaching some point, voltage on the inverting input of the comparator becomes higher than the non-inverting input and the output of the comparator becomes LOW. And then the capacitor in the negative feedback path discharges and the voltage on the inverting input becomes smaller than the voltage on the non-inverting input, causing the output to go HIGH again. It goes on like that.

But the thing is I am not able to understand the effect of LC tank circuit here. I don't know how come the output frequency is equal to LC tank resonance frequency. And I am not able to understand the function of the resistance between output and non-inverting input of the comparator.

A comprehensive explanation of the circuit is the given in the link below :

http://www.vk6fh.com/vk6fh/lc_meter_vk6fh.htm