two transistor sine wave oscillator 20 Hz - 19,2 KHz

Schematic, layout and pictures from a two transistor (Wien bridge) sine wave oscillator (prototype) that works between 20 Hertz (15 Hertz) and 19,2 KHz. Easy to make, a real beginners project. Including a schematic from the power supply and two schematics from 1 transistor amplifiers/buffers to which the generator can be connected. The circuit works on 12 Volt. Copyrighted content. UPDATE 4 november 2022: I re-tested the circuit and found that not all 6 Volt/0,6 Watt bicycle lamps work. When the sine wave generator does not want to start replace the 6 Volt 0.6 Watt bicycle lamp with a wire wound resistor of 100 Ohm. You can also use smaller capacitors (1N and 560 pF, must be ceramic types) to go to somewhat higher frequencies.