Found in Texas Instruments documentation from the 1980s, this circuit applies to digital signal transmission with FSK modulation. The circuit is slow, as it uses period components.
This two-transistor amplifier can be used as power stage for intercom, experimental receivers,...
This proximity relay circuit was found in the July 1990 Radio Electronics magazine. The supply...
With an ultra-low consumption, this circuit can be powered by solar cells. The circuit is from a...