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 1977 RCA manual of integrated circuits. The company no longer exists, and...
This circuit was found in a 1967 Japanese documentation. It consists of a touch control system with...
This amplifier uses transistors from the 60s, having been found in documentation of the time. The...