The reader mechanism shown was purchased from All Electronics for $1.50. The unit provides the magnetic head on a spring mechanism along with low level head signal amplifiers and data slicers. Three signal lines comming from the unit provide card presence, clock, and data. When actively reading a card, it draws about 50ma of current at 5 volts.
The data from the unit appeared to be 'track-2' format. This is 4 bit plus odd parity data. The data is readily converted to ASCII by adding Hex-30 to each nibble.