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.
-- We find this configuration very simple in a previous American publication of 1973. The...
Bis This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine. The...
This small audio amplifier circuit in complementary symmetry was found in the 1974 Mullard...