This app will help you to find
resonance frequency of coils. This is a inductance meter

This app will scan your coil then show you the resonance frequency of your coil and the inductance!
This app use headset microphone input to connect to the coil!
To build the measuring leads you will need:
1 - MiniJack 3.5 with 4 pins.
2 - Resistance 10k and 100R
3 - Capacitor of 220nF
4 - Cable
4- Transistor BC557 (2 units)
You can find more information about this inductance meter - resonance finder on my web page!