The integrated circuit used in this 2002 project is not very common. It is powered directly by the telephone line, requiring no power supply.
The circuit presented was found in the 1994 National Instruments Linear Applications Handbook and...
We found this circuit in a 70's RCA manual. The circuit provides 0.5 W power in the 700 MHz to 1...
This old circuit uses two light-sensitive SCRs or LASCRs. The circuit drives small loads. The...