This two-year-80s circuit consists of a solution for a small portable recorder powered by cells, as it was used at the time. The circuit can serve as a reference for the recovery of old equipment.
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...