Having just finished a few minutes ago adjusting a reed switch to minimize the double trigger I appreciate the problem. The Super Chuffer elegantly varies the on time of the fan motor with changes in chuff rate. I have used a one shot (monostable multivibrator) to shorten the on time and give distinct puffs up to higher speeds before it appears as a steady stream. While simpler, it doesn't change the on time of the fan at slower speeds like the Super Chuffer. Neither does it fix overlap. That requires sufficient distance between the magnets and reed switch so its closed for the minimum amount of time.
The optical solution makes it much easier to do this.
Pete
