This is a measuring resonance of very low frequency (vlf). This video shows an easy way to measure the resonance for coil on very low frequency. The frequency range is between 5kHz-30kHz. this video also provides the circuit that is used to measure the resonance of the coil. On this video, to measure the resonance of VLF coil, the 370ohm resistor and the 39nF capacitor are used. Its very important that the output level of the sine generator is not very strong, when its too big we can’t see the resonance picture. The circuit is connected to the sinewave generator and the oscilloscope. When the frequency is set to about 18 kHz, we can see the resonance picture on the oscilloscope and when the frequency is too big the resonance picture do not show up on the oscilloscope. Here is the video tutorial: