This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an auxiliary relay with the call signal for a possible louder bell.
We found this circuit in a 1968 Electronics World. The transistors are from the era and...
This circuit, which generates a linear sawtooth signal, can be used in a frequency-band...
The instrument of this field strength meter, from a 1970s publication, can be a 200 uA...