Wien-bridge oscillator, LM324
Électronique / Electronic
AOP / OP AMP

In this project, you're going to build a Wien-bridge oscillator, a variation of CR oscillator.

Wien-bridge oscillators are commonly known as a circuit capable of producing sine waves with good characteristics. When you finish wiring, turn power ON.

You should be hearing a monotone from the speaker. Try to rotate the control volume. What happened to the tone?

You'll notice the tone getting louder or quieter as a result of change in gain. This oscillator resonates at a certain frequency. The resonation is obtained by combining the positive feedback section of the OP amplifier U1A with a serial CR circuit and a parallel CR circuit.

These Cs and Rs are the bridge elements, and the oscillating frequency is given by the following equation

(R = R4 = R3, C = C3 = C2):

F = 1 / (2πRC)

In this circuit, a diode limiter is used for limiting the signal amplitude. The circuit used in this project is simple, and that's why the temperature characteristic of amplitude and distortion factor are not very good.