This circuit uses a contactor having been found in a 1987 publication. More modern equivalent devices may be used. The circuit has neon indicator lamps.
This receiver uses only one transistor but has excellent sensitivity to the mid-wave range. The...
This six-decade logarithmic current amplifier was found in a 2005 Linear Technology manual. The...
This 3V-only circuit was found in old American documentation, but can be implemented with...