Wien Bridge Oscillator

This AF oscillator can be built with only one active compo- nent, and draws so little current that it is conveniently fed from a 9 V (PP3) battery. The basic circuit of the Wien bridge oscillator is shown in Fig. 1. The oscillator consists of two sections, namely the opamp plus R3-R4 which deter- mine the amplification factor, and positive feedback network Ci-Ri-C2-R2 which enables the circuit to oscillate. This network is composed of a low-pass sec- tion R2//C2, and a high pass section Ri+Ci. The phase dif- ference incurred in these is nulled at the frequency of oscil- lation, when the filters form a pure ohmic potential divider WIEN BRIDGE OSCILLATOR with an attenuation of 3. There- fore, the opamp must have an amplification of 3, to keep the overall amplification at unity, so that the oscillation is main- tained. The output frequency, fo, of the oscillator is fo=1/(2n"[RiRzCiC2) [Hz] but only if RI -,,122 and CI In the practical design shown in Fig. 2, the oscillation frequency...