This circuit was obtained in an 80s documentation on telephony. The components used are TTL, and the power must be made with 5 V.
We found this circuit in an Electronic Engineering of the 90s. The circuit can be implemented with any...
I found this circuit in an article in a 2003 publication. The circuit is an example of how to...
We found this circuit in a 1975 publication. The power supply must be symmetrical, but other...