Found in a 1967 RCA manual, this circuit uses components from the era that can be replaced by modern equivalents. The circuit is for resistive loads.
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...