I had an idea a while back. I rented a van in Florida for our family vacation last year. Not sure if it was a good or bad thing but as the engine power would fluctuate it was noticeable that the blower speed fluctuated (like the battery was dead and the alternator was the only thing powering the blower). Anyway it reminded me of a similar effect in a jet – since the cabin air is taken off a stage of the engine compression it would change the pressure and noise level in the cabin almost directly. Then I went to the Sigur Ros concert in Kansas City last Thursday and saw they were independently controlling incandescent lights on stage! My friends at Phidgets led me to this article which lead me to Proportional SSR’s and voila!
Ah, but sadly Crydom recommends against using these for inductive (motor, transformer) loads. Not sure why or what would happen so I bought one on eBay to experiment with. In the event that my experiment goes horribly wrong:
Fortunately the blower motor that we are using has a tapped winding and I could switch between these three speeds using a standard AC SSR.
In other news, finished the forward bulkhead insulation and moved onto the starboard interior paneling. That is ready to paint with the kids tonight!