Found in a 1964 Electronic Design, this circuit shows how to modulate a signal with a dynamic low impedance microphone. The circuit operates in the FM range (88 to 108 MHz).
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...
This circuit is from a 1965 Electronic Design. The transistors may be general purpose and the...