This 4-tube counter was found in Radio Electronics magazine from December 1959. The circuit uses a coil as a sensor to detect the passage of metallic parts or magnets.
This circuit was found in a 90's Electronic Design. It takes advantage of the nonlinearity...
This sensitive Japanese mid-wave receiver from the 1960s has an output power of 45 mW and is...
This sensitive MW receiver was found in a publication of year 1958., The circuit uses germanium...