This circuit was found in the January 1989 issue of Radio Electronics magazine. The circuit sends audio signals by modulating a low-frequency carrier through the power grid.
This fully passive circuit was found in documentation from the 1970s. The circuit uses an optical...
This circuit of old documentation is based on an operational amplifier that is no longer used...
This circuit was found in a Japanese publication from the 1960s. It uses germanium transistors and is powered...