Product: Ventilation fan for marine application. Speed adjustable via trimpot knob.
Needed: Please design a compact circuit adequate for marine environment that will power 12v fan and can be adjusted via 10k Trimpot or similar.
Details: A few fan manufactures allow adjusting fan speed via trimpot but I can't find stock. I've seen a few designs for PWM with 555 timers but circuit needs to fit inside the fan case and work with 12v. Heat dissipation should be minded as case is plastic.
* Find 12VDC, 80mm x 80mm, IP68 fan. Perhaps something like:
* Use trimpot to adjust speed. Something like this one or in the same package: http://www.digikey.com/product-detail/en/bourns-inc/3386F-1-103LF/3386F-103LF-ND/1088491
* Shopping list, preferable Digikey, ensure available stock.
* Layman's circuit design.