Tiny13 Sawtooth CES Design
In the first Tiny13 CES Machine design, we used a Biphasic rectangular Pulse Base Band waveform. However quite a number of people have asked whether it would be possible to use Saw tooth waveforms instead.
We take account of the fact that the Tiny13 has two hardware PWM peripherals on board and that we can use them to generate the appropriate Saw tooth wave forms. Unlike the previous design, we generate a fixed frequency saw tooth of 146.5 Hz in PwmB and a variable, randomly chosen saw tooth frequency between 147 and 161 Hz in PwmA. The body doesn’t sense these "Carrier" frequencies but rather, Binaural fashion, only the difference between these two frequencies. For example, if we output a wave form of 150 Hz on the PwmA output pin and keep the frequency at PwmB pin at a constant 146.5 Hz, then the body will sense and respond to the 3.5 Hz difference frequency only.
Aside from the fact that the Saw tooth version uses an On/Off Switch instead of a Push Button, the Schematic remains pretty much the same as in the original. The same can be said for the code.
John-Alfred Ullasmann
2006-07-17
Tiny13 Sawtooth CES Machine Circuit Diagram:
Code:
