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Originally Posted by joesgarage11
Maximilium, why did you use two separate ICs?
I'm having trouble understanding this part. Can you explain?
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Back when I was testing the ULN2803 on a single fan I had some weird R.P.M variations, I was powering the IC directly from the power suply, not from the motherboard fan conector. It was only when I power the ULN2803 from the motherboard fan conector when I got it working . The uln2803 are cheap (.70 cents each and I order 4 to be exact), just to play safe I end up using 2, 1 IC for each Pump, but you only really need 1.(in theory you can monitor 8 fans/pumps from a single ULN2803 )
When resistance is applied to the impeller base R.P.M will decrease. What I have both pumps runing without the impeler housing ( yes, too lazy to build a test water circuit loop, and if you run the pump without water you will damage the impeler). This pump is a Mag-drive pump , this means that the impeler is moved by the magnet behind the impeler housing . with the impeler housing removed , Powering the motor and (very carefull) using my finguer to stop the base magnet R.P.M. whent from 4200 to 3800.