A little design help...

[Michael Vickers]

Sorry, I should have checked the 72V .55A rating (or 12V 3.3A parallel). I didn't think that a fan drew that much.

[L. Daniel Rosa]

Dacflyer,<p><chuckle> Is there a return address on the package? Seriously though, for some of the same reasons you don't want your e-mail address readily available on the web, I don't feel comfortable posting my s-mail address here. You could send me an e-mail and I'd respond with it though, if you've already thrown the box away.

[Edd]

L Daniel Rosa....in Fluke,Boeing and Tek country(proximity).
I had salvaged some 6 in brushless DC fans that were mounted on a polycarbonate panel . 8 units in a 2 X 2 ft sq area. I stacked 2 panels
vertically and have them supplementally cooling my refrig's condensing coils at its rear. Each fan on 12VDC pulled only 260 ma. A bit more that the typical 3in computer fans ~ 120ma. But your units 550 Ma is quite a pull.
I considered nothing other than a linear supply, with an isolated ferrite balun, current sensor on the compressor line, feeding into control
circuitry for its activation.The unit has really shortened its run times.<p>I'm quite leery on your series hook up, but particularly on the ripple factor that U had planned on hitting them with . Current day DC
brushless fans have their electronics condensed to the point that the Hall sensor and all its conrol electronics has a footprint of less than 1/4 of a TO-92 casing, with only the discrete stator driver xstrs separate. I've seen some that even incorporate them, in a bit larger
footprint, with a heatsink tab.
I feel that Hall sensor and its circuitry will only tolerate a SMALL FRACTION of that specified ripple and be able to operate.<p>73's de Edd<p>[email protected] (Interstellar~~~~Warp~~~~Speed)
[email protected] (Firewalled-Spam*Cookies*Crumbs)

[L. Daniel Rosa]

Good point Edd. I'm testing one right now to see if it can withstand that much ripple for a few hours. I set the variac at 20V to get the same speed.<p>I've opened up fans of tow different voltage ratings and found they have the same propietary chip. There are some rated for 48V, but I haven't looked in one of those yet. If this unit can stand the abuse I'm putting it through, I'll probably omit the filter entirely.<p>Thanks for the feedback, Edd.