This circuit was found in a Popular Electronics of the 1980s. The microammeter may be the lowest current range of a multimeter. The antenna is telescopic.
This SCS counter circuit was found in a 1964 General Electric documentation. The circuit has a...
This simple 1-transistor reflex receiver was published in Radio Electronics magazine in September 1959....
Operational amplifiers used in this 80's circuit is not very common today, but the setting can be...