This circuit uses a quadruple operational amplifier of the time. The circuit is from the 70s but can be implemented with modern operators that require the use of a symmetrical source.
This shortwave preselector was found in the July 1994 issue of Radio Electronics magazine. The...
This circuit was found in a 1980s American documentation. The data circuit has a low speed,...
This simple alarm with latching uses a relay as the main element. The circuit is from a Radio...