Calculating resonance frequency of a bifilar coil

Joined Jun 22, 2017
11
Hello everyone!

I'm building a bifilar coil to transfer power wirelessly. to generate the signal for transmitter coil, I'm building my own function/signal generator with this youtube video -
. but it doesn't work well with higher frequencies (1-10MHz) . So my question is how can I lower the resonance frequency of my bifilar coil by changing its diameter, windings, winding direction, length? is there a equation for calculating the resonance frequency of a bifilar coil with factors like its windings, diameter, length, direction? I'd like to keep the resonance frequency as low as possible and love to transmit a considerable amount of power with this. the coil setup is similar to this except there is no mobile phone and permanent magnet. Please explain your answer in simple words, I don't have a lot of knowledge in Mathematics or advanced electrical engineering ( I'm 16 ) Thank you!

DickCappels

Joined Aug 21, 2008
10,104
Add parallel capacitance to tune it.

Joined Jun 22, 2017
11
Add parallel capacitance to tune it.
Sir, can you please explain it more.... Sorry I'm a new to electronics... I want to calculate the resonance frequency of a coil with certain diameter, length, windings so I can buy the necessary gauge wire that creates a specific resonance frequency

DickCappels

Joined Aug 21, 2008
10,104
If you know the inductance of your coil you can calculate a capacitance to put across it to make is resonate at a particular frequency. I have sent a link to an old project with similar requirements

The key relationship is used to find the inductance and capacitance needed to achieve the desired resonant frequency.

Feel free to have C and L swap places so you can calculate C if you know L.

Please see the web page at the URL I sent in the private message.

Last edited:

Joined Jun 22, 2017
11
If you know the inductance of your coil you can calculate a capacitance to put across it to make is resonate at a particular frequency. I have sent a link to an old project with similar requirements

The key relationship is used to find the inductance and capacitance needed to achieve the desired resonant frequency.
View attachment 233503

Feel free to have C and L swap places so you can calculate C if you know L.
View attachment 233504
Please see the web page at the URL I sent in the private message.
Sir please look at questions I've sent to you in private DMs.

Janis59

Joined Aug 21, 2017
1,783
More prost is to wind something similar to the aim and then MEASURE the resonant point as well the mutual inductance ie link factor.

Joined Jun 22, 2017
11
More prost is to wind something similar to the aim and then MEASURE the resonant point as well the mutual inductance ie link factor.
Would be nice if you can explain it more!

Janis59

Joined Aug 21, 2017
1,783
By Google You shall find very simple mutual L measuring technology. Most prost but not very accurate is point the measurer of inductance to primary and read two figures, at shorted output and with interrupted output. More accurate figures comes out, if repeat this measurement from side of output and open or close the primary. Then all four (or two) readings put in the due formula and voila! Just push the Google button.