We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the power supply which can consist of 4 batteries or a 9V battery. The basic circuit uses two-color LEDs.
The circuit shown is only for analog telephone lines. I found it in Popular Electronics (1991). It...
June 2016 - Mouser can immediately deliver the TPS54xx plate for experiments with Buck converters from...
The circuit shown in the figure is triggered by an input voltage determined by the setting of P1....