This circuit was found in RCA documentation from the 1980s. The circuit uses LDRs of the time and the 50 uA instrument has zero in the center. R1 and R2 may have 2k2 and R3 10k typically.
This remote-control circuit was found in Radio Electronics magazine from June 1962. It drives a...
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...
This circuit with a few watts of power was found in the April 1995 issue of Electronics Now...