This resistance meter was found in an English documentation from 1989. The operational amplifier admits an equivalent and the transistor can be a BC558 or BC559.
This circuit has the muting action delayed by the action of C5. The circuit is from the SGS linear...
This circuit was found in the November 1959 Radio Electronics magazine; The circuit generates a...
The integrated circuit used in this detector is uncommon today. We found it in a documentation from the...