This 555-based circuit was found in the August 1976 issue of Radio Electronics magazine. The tone frequencies are provided by the capacitors connected to the 555 IC.
The transformer of this unit found in an old Japanese documentation can have 22 to 25 V of...
This JFET amplification stage was found in the April 1993 issue of Electronics Now. The input...
This circuit with two power transistors was found in Radio Electronics magazine from October 1960....