By Michael A. Shustov (Russia) and Andrey M. Shustov (Germany)


It is said that the sight of flames flickering from an open fire or the sound of the ocean rhythmically breaking on a beach has a calming affect on us. Nowadays you can easily install a cozy fireside scene for use as a screen saver, but a stand-alone unit producing soothing ocean sounds? Now that’s something else…

The circuit in Figure 1 to generate the realistic ocean swell sound is made from discrete components. It consists of a white noise generator, a square wave generator, filter and summing network to produce the envelopes of white noise which are fed to the input of a low frequency amplifier and out to a loudspeaker.
 
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The white noise generator (around T1) is a super-regenerative detector circuit like those used in the designs of old radios. The pot R2 is adjusted so that a strong white noise signal is output at point A. The operating frequency set by the resonant network made up of L1 and C2 is not critical and can be changed if necessary.