How to generate 30Hz sine wave?
Your friend, the Wien-Bridge oscillator.



Uses just opamps and resistors/capacitors. produces very clean sine waves in the low frequency range. There are many variations, with C=C1=C2, R = R1=R2, it oscillates at \$f = \frac{1}{2\pi RC}\$. Rb is a lamp used for temperature Compensation, although there are many variations don't require it, for instance, using zener regulators like such.