This circuit uses a 555 (according to the diagram) to generate 50 ms tone bursts at a frequency of 1.5 kHz. The circuit is from an 80's Electronic Design.
This Intersil circuit was found in a 1980s documentation. Operational are of the time, but current...
New Low-Power PIC24 “GA7” Microcontroller Family Now Available CHANDLER, Ariz., Dec. 12, 2016 — The...
This circuit was found in a 1976 NASA manual, making use of components of the time. The transistor...