This circuit was found in a 1980s US publication. It indicates when the phone is off-hook by triggering an indicator.
This circuit was found in documentation from the 50's. The circuit uses transistors of the time...
This dual circuit was found in an 80s Siliconix documentation. The power source must be...
August 2016 - Mouser Electronics is already providing new MKR1000 Arduino board, a practical...