I was wondering if anyone has made a very low frequency sign wave oscillator.
I've been working for some time on a project called the Harmonic Wave Transducer or Purr Generator. I have attached several transducers under a bodywork table and am finding that frequencies between 10 and 20hrtz make human tissue much easier to work with. Cats purr between 10and 20hrtz.
What makes this cool is overlapping 2 waves that makes a 3rd biaugural wave that is very pleasing. I'd like to overlap the waves on the fly using arduino instead of the computer program I currently use. I'd also like to adjust amplitude.
I'm something of a rube when it comes to electronics, and am learning the slow way. Any help would be appreciated.
The standard way of making waves low or high frequency is to use an external digital to analogue converter. With the arduino there is a sort of crude analogue output using what is called the PWM (pulse width modulated) mode of some pins. This requires a filter using at least a resistor and capacitor to smooth the output.
It is not very suitable in your case as the PWM frequency is very close to the frequency of waveform you want to generate so you will have to have a better filter or increase the PWM frequency both of which can be done but are non standard.
Look in the playground section Arduino Playground - HomePage for audio applications and techniques, especially those that involve an external D/A.
Low frequency sine waves are easy to generate using a lookup table (actually, any function is easy with a lookup table!) and a simple R-2R D/A converter if you've got sufficient output pins available.