Abstract: An improved system and method for adjusting an air gap in a core portion of an ignition coil includes a low-cost circuit for providing real-time determination of an inductance of one of the windings of the ignition coil being assembled. The circuit includes an AC power source in series relationship with a resistive element and the ignition coil. The circuit further includes a controller, such as a programmable logic controller (PLC) to read voltages across the resistor and ignition coil and calculate an inductance, using data determined in a calibration step. A machine is controlled to adjust the air gap until the calculated inductance equals a desired inductance. Reduced cost, and improved immunity to TIG welder noise is provided.