Stick the PWM heatsink in the airflow.
50W PWM solutions are around 50-90$US, so nice solution :-)
o If you run it off a PC PSU tail, fuse it but add in a relay with
diode protection to run a 12V beeper for fan (fuse) failure.
o Yes fans going silent should be a good cue, could be missed.
Also, if you can vary your PWM frequency, do so because you
may be able to knock a few more dB(A) off your noise levels.
It can certainly affect the qualitative aspect of PWM fan noise.
--
Dorothy Bradbury
http://homepage.ntlworld.com/dorothy...ry/panaflo.htm (Direct Prices)