inputs on pin 15 counter 116 is always enabled because the enable input pin 13 is tied to ground but this counter will only count after counter 114 has registered an input of ten pulses and counter 114 is only enabled when j k flipflop 119 is set and the ground at the k input is reflected at the q output the sequence of operation involved in enabling and resetting counters 114 and 116 commences when light beam receiver 38 senses that material has passed out of the immediate sewing area by completion of the light beam and generates a signal at input 120 this signal is applied to the base of transistor 121 which has its emitter coupled to the negative bus of the sewing machine control logic card and its collector connected to the positive bus of the sewing machine logic card via light emitting diode 123 and input pin 124 when transistor 121 conducts light emitting diode 123 becomes illuminated and the photoresponsive portion 124 of photo isolator 125 becomes conductive this causes schmitt trigger 110 to produce a positive pulse that clocks j k flipflop 126 and causes the ground potential at the k input to be.