Nostalgic Sine Wave Generator

As far as young engineers and techni- cians are concerned, a sine wave gener- ator is something you make from an XR2206. In the pre-IC era, sine wave generators were designed around discrete components. The generator 58 SUPPLEMENT described here has, however, more than just nostalgic value: it is also educational (and perhaps suitable for writers of the history of electronics). The (fixed) output frequency is fairly stable at 1 kHz, and the distortion, after proper adjustment, below l%. The gen- erator is suitable for use as an audio test generator or as a morse code trainer and costs only a couple of pounds to make. The generator is of the so-called NOSTALGIC SINE WAVE GENERATOR double-T type, which has the advantage of not needing any inductors. The oscil- lator proper, Ti, is followed by an emit- terfollower, T2, which ensures a suffi- ciently low output impedance. The frequency is set to 1 kHz by Pi, and P2 minimizes the distortion of the wave- form. With P2 set for minimum ...