The operational amplifier used is not common today, but the circuit can be implemented with modern operational ones. The gain is 1000 and the source must be symmetrical.
Suggested for use in cars and motorcycles, this circuit was found in a 90s Popular Electronics. The...
This is a typical 3 ½ digit TTL counter. We found it in the September 1973 issue of Radio...
This receiver, whose tuning range depends on L1 and L2, was found in the 1992 special edition of...