Using a varactor or varicap, this 1969 Electronics World circuit has a modulation range from 75 kHz to 52 MHz. Modern equivalent components can be used.
The SCR used in this 80's circuit depends on the load. The control is half wave and instead of the neon...
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
Found in Popular Electronics this circuit will trigger a buzzer if the ignition key is removed...