 Unwanted trigger impulses in early attempts at using SCRs for CD ignitions were caused by electrical interference, but the main culprit proved to be 'points bounce'.Points bounce is a feature of a points-triggered system.In the standard system with points, distributor, ignition coil, ignition (Kettering system) points bounce prevents the coil from saturating fully as RPM increases resulting in a weak spark, thus limiting high speed potential.