Found in American documentation from the 1980s, this circuit has a throughput of 700 Hz and a flat response of 400 to 500 Hz, with crystals of 3 MHz. Crystals of 2 to 15 MHz can be used.
This reader with TTL logic compatible output uses an LM139 comparator. The circuit was found in...
This circuit can be used with common transistors, from general purpose to medium power. The...
Although it is a common configuration today, these circuits were taken from an old publication. The...