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RC Audio Oscillator
Here is the design of an audio oscillator that runs at approximately 1 KHz. I don't remember where I got this circuit, probably from EMFRD, since Wes's book is a treasure trove of useful circuits. This handy oscillator can be used as a source of audio for testing out audio stages in receivers and the like, or as a stable signal source for testing microphone circuits in transmitter. 
Audio Amplifier Schematic
A schematic of the audio oscillator. What is not shown is the 8-volt regulator circuitry that is part of the finished module.  Just use your favorite part and circuitry there, it isn't critical at all.
RC Oscillator - View1
This  photo shows how the RC Audio Oscillator was built.

The 8-volt regulator is the taller 3-terminal device to the rear with the tantalum capacitors on either side.

A small "U" bracket is soldered to the PCB substrate to support the level adjusting output pot.
RC Audio Oscillator - View2
This view shows a bit more detail of the 0.01 uF capacitors, the red-orange units in the foreground, used along with the 5.6K resistors to set the frequency of oscillation. These capacitors can be changed for a higher or lower audio tone.
RC Audio Oscillator Output
This is a scope plot showing the output of the RC Audio Oscillator with the pot set for maximum signal.

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