In this book the circuit diagrams are the predominating feature. They are arranged in a logical and progressive manner, following generally the historical development of the art.

Because Art. 800 has its roots in telephone technology, it addresses telephone and related systems that use twisted-pair wiring. The telephone utility typically provides the twisted-pair cable to a ...

This circuit can be placed anywhere on the phone line, before or after the phone. Now connect a mini jack audio cable from the circuit to the line in on your audio card or recording device.