This reader with TTL logic compatible output uses an LM139 comparator. The circuit was found in the 1994 National Semiconductor Linear Applications Handbook.
This circuit is from a documentation from the 70s. The circuit uses logic gates of the time, which...
We found this circuit in the October 1988 Radio Electronics magazine. The circuit is still current...
This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit...