This circuit was obtained in a documentation from the 70s. The operational amplifiers used are uncommon today. Modern equivalent types can be tried out.
This LM380-based circuit was found in documentation from the 1980s. The components are current, and...
This circuit was found in documentation from the 90s in Europe. The circuit shows how to vary the...
Great sensitivity for the circuit can be obtained with a Darlington amplification step for the...