Abstract: An inductive pickup sensor employing an isolation transformer to achieve substantially improved immunity to capacitively-induced cross-talk signals is provided. A magnetic pickup coil is coupled to a spark plug wire to receive a spark signal. The spark signal developed across the magnetic pickup coil is then coupled to via a sensor cable to the primary winding of an isolation transformer which is configured to provide a relatively low interwinding capacitance level to substantially reduce the cross-talk signal amplitude relative to the spark signal at a detector circuit. The detector turns the spark signal into a trigger signal at a pair of output terminals.