The above will give you values ranging from -1 to 1 'f' times per second. If you want to remap the output then I recommend the linear() function:
linear (s, -1, 1, 0, 100);
The 2nd and 3rd arguments (-1 and 1) are the input range and the 4th and 5th (0 and 100) are the output range that 's' is remapped to linearly. Try changing these numbers around to clip the pulse in interesting ways.