We found this circuit in a 90s Popular Electronics. The circuit uses a pickup coil that consists of 100 to 200 turns of wire 28 around the cable to be monitored.
This sequential beacon was found in an 80's Radio Electronics. The circuit can be designed using modern...
The operational amplifier used in this circuit of an old documentation no longer exists, but the...
We found this trebble booster circuit in a 1990 documentation. The components are current, and the...