Simple Wien-Bridge Oscillator circuit without AGC or nonlinear gain compensation.
The non-inverting input (+) is fed the output signal through a series RC circuit (Low Pass Filter) and a parallel RC circuit (High Pass Filter) with a 0deg phase shift at the resonant frequency ( found by 1/(2(pi)RC) ). This circuit forms the feedback circuit.
The inverting input (-) is fed the output signal passed through a voltage divider circuit used to set the gain of the amplifier. The gain of the amplifier should be equal to the feedback fraction so that the overall gain is 1 and the oscillations will be sustained.
Gain = 1+(RF / RG)
Gain too high = op-amp saturation/clipping
Gain too low = oscillations decay.
Give the circuit a kickstart by injecting some noise to initiate the oscillations.
Questions, Comments, Concerns. Give me a shout.
