Re: using smaller caps: i should have remembered that, since electrolytics tend to be bad at suppressing high-frequency noise.
I'm thinking that there'll be components of both RF ringing as well as larger, longer-lasting (milliseconds or so) spikes - so maybe a small ceramic or film cap (between .01 and 1uf) as well as a larger electrolytic (100+ uf) might be best for filtering noise. The diode certainly can't hurt either.
Since87, if you're going to be testing this on an oscilloscope, i think we'd all appreciate it if you captured waveforms with and without filter circuitry so we could see the difference. Thanks.
Quote:
Originally posted by nexxo
I'm starting to wonder whether there are several versions of the pump in question around... especially as mine, and the CM10P7-1 a.k.a. Jabsco, are described as "ball-bearing permanent magnetic drive". No brushes there.  No mention is made of capacitors, but it says to make sure the motor housing is connected to GND (say, the PC case) and to have a fuse in-line. 1.6 A for the CM10P7-1, and 3 A for the CM30P7-1.
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Nope, i'd bet my pump
that it's brushed. it still has permanent magnets in it - but in order for a motor to operate off of DC, it's either going to have brushes or have some driving circuitry (which is what you find in brushless fans) that would have to have some subststantial heat sinking in order to run a pump of this size.
The reason the manual doesn't mention capacitors is because marine/car electrical systems don't tend to have extremely noise-sensitive equipment attached without some sort of power regulation or filter circuitry in place.
and one last time for any n00bs reading:
brown wire is negative, blue positive.
so on a molex, brown goes to black, blue to yellow.