In the figure we have a simple way to obtain (almost) sinusoidal signals from an integrated circuit 555 operating as stable. The frequency depends on R1 and C1, according to formulas that can be obtained in the math section of the website and the filter capacitors on the output depend on the frequency, and should be tested in the range from 470nF to 100uF, depending on the frequency of the sinusoidal signal. The power supply must be between 5 and 15 V and the maximum current is around 20 mA. The load resistor also depends on the waveform and current required by the powered circuit.
