I have a question about a bilifar coil. First I need to set the image, You have a opposing bilifar coil so as to decrease the inductance of the coil. http://en.wikipedia.org/wiki/Bifilar_coil 1 Winding will be coil A and the other coil B just so we can all know which coil turn we are all talking about. Now the question I have is what happens when you power up the bilifar coil to steady state and then shut down, let's say coil B? What happens to coil A? I believe that Coil A will have a temporary Voltage increase since Coil B would be inducing a voltage opposite it's own voltage. What effect will Coil A's own inductance have on it's self since as coil B is decreasing , coil A's inductance should be increasing until Coil B is fully off. Would this inductanc increase somehow lower Coil A's voltage and thus current and thus it's total Magnetic field porduced, it is already at steady state though and no long powering up? 2nd part of the Question is: What happens to Coil B when it powers back up again, I mean what inductance would it encounter. Would Coil B's inductance be that of coil B as if it was just a single coil without coil A? or Would Coil B's inductance be what is was before when both Coil A and B were powering up, very little because they are opposing each other? For the 2nd Part or the question, I am not sure what will happen, or the first part for that matter. I think that since Coil A is still on and producing an opposing field to Coil Bs, that coil b's inductance would still be very little and allow it rise to steady state much much faster than if was seperate and there was no coil A creating a opposite Magnetic field.