It is a generally known and accepted fact that servos used in radiocontrolled models see very little or no use outside the model flying, racing or boating season. A pity, considering these devices can be used for many useful tasks…For example, a servo that’s not used anyway could be attached to a large pendulum of which the smooth and steady motion may help people relax and even fall asleep. For this (psychological) effect to be achieved the movement has to be sine-shaped like that of a real and very long pendulum.The small circuit of the Relaxation Machine you find in Figure 1 consists of two parts. A pulse generator based on a 555 supplies positive pulses with a length between 1 and 2 ms (‘mark’) and a pause of 20 ms (‘space’), representing a typical servo control signal. In addition there’s a sinewave generator designed to supply a very low frequency of about 0.25 Hz which corresponds to one full period in four seconds. The sinewave generator employs a phase shifting network and supplies a sinewave with very low distortion. If you want to lengthen the period, simply increase the value of C1, C2 and C3 a little.