Audio Oscillator    WB9YBM Analog Audio Oscillator:  QST, February 2017, pages 46-47 This circuit is not a kit (yet)... I constructed it first on a breadboard and then transferred it to a generic PCB (the leftover half of a board that Id cut in two for the N4YG oscillator modifications).  It was fortunate to have tested the circuit on a breadboard first, as the diagram in the QST article misidentifies the output of the 741 op. amp. chip as pin 5.  It is pin 6.  Upon correcting this error, the breadboard circuit functioned as described in the article.  However, I prefer a lower frequency tone, so tried a few combinations of R1, R2, and C2 + C3.

Tone frequency as function of RC
    Then I had the idea to connect R1, R2, and the capacitor to an 8-pin header that could be unplugged and swapped if desired, a poor man’s tone control. Another sort of crazy reason for doing this is that I did not have any 8-pin dip sockets at the time, and thought it would be a good way to fill up the empty half of a 16-pin socket for the 741. The RC values in the photo are 0.1 F for C2 + C3 and R1 = R2 = 10K. 

    Analog Oscillator: WB9YBM_oscillator.mp4

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