A low-distortion sinusoidal signal in the audio range is an indispensable tool, for example, for setting the correct quiescent current of an audio output stage.
A simple means of choice is the generation of the sine signal with a so-called Wien-Robinson Bridge. An operational amplifier serves as an active component.
It is also interesting to use an incandescent lamp (not a glow lamp!) as a PTC resistor to stabilize the circuit.
Since a low-cost 4-fold operational amplifier is used, a Schmitt-Trigger can be set up with a remaining OPA, which additionally provides a square-wave signal.
Another OPA generates a symmetrical supply voltage (with virtual ground). The whole circuit is very simple, fast built up and a very helpful audio test generator.
Data:
Frequency: 166 - 8150 Hz
Amplitude: 0.2 - 4.8 Vss
Power: 12V, 30 mA
 Wien-Bridge |
 Sinus Wave |
 Square Wave |
 Schematic |
