This circuit was found in documentation from the 90s. The operational amplifier is NE5514, which is uncommon today. The configuration can be adapted to use modern components.
We found this circuit in the Linear Applications Handbook of the National Semiconductor of 1994....
This simple continuity tester, whose configuration can be found several times on this site, is...
This circuit is from old documentation. The operational amplifier is uncommon nowadays. The...