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 circuit in an American manual from the 80's. The circuit can be implemented with more...
1E) This circuit was found in a Popular Electronics from the 90s. The circuit generates different...
This circuit was found in an 80's Radio Electronics. The circuit makes use of general purpose...