This circuit is from a 1968 documentation using one of the first integrated circuits available at the time, the TAA370. The circuit is powered by 1.3 V using a 200 ohm handset.
This circuit for experimental radios and other applications is from a documentation from the 50's....
This circuit with JFET and Unijunction was found in an ancient American documentation. The...
November 2016 - NXP ARM Cortex microcontrollers for serial interfacing applications, NXP 32-bit...