This high-precision circuit was found in documentation from the 1990s. The integrated circuit is an LM111 or another in the series. The circuit has TTL output and can function as a shield.
The circuit below shows how to use an LM139 comparator or series equivalent as an amplifier. The...
We found this receiver circuit for modulated light in a 90s Popular Electronics. Equivalent audio...
The circuit was found in the February 1992 Radio Electronics magazine. The scale can be changed by...