Abstract: A bit stream encoded in the Aiken or similar selfclocking code is converted into binary waveform with clocking by a sensor including two sensor elements spaced apart a critical distance. The elements read the bit stream independently. A logic circuit responsive to the outputs of the elements determines the data content of each bit as well as the timing of that bit.The apparatus permits code conversion of, for example, credit cards at point of sale (POS) apparatus independent of variations in the movement of the code (viz: credit card) with respect to the sensor.