Don't need caps - just a rectifier (either diodes or a bridge). Not like motors need smooth power really.
I've actually seen that sort of setup in a hairdryer I cut open - it had the AC line coming in, then a bridge rectifer and a DC brushed motor.

Howdy all, long time reader but first time poster....


Was at Lowe's over the weekend looking at thier mag drive pond pumps. I noticed they are carrying a new brand and many of them had the volute design to them.

I'll try to explain (excuse for my bad english):

AC regular motors use iron build rotor (squirrel cage). They need any art to get direction. Usually shaded or delayed coils.

http://upload.wikimedia.org/wikipedi...ole_detail.jpg
http://upload.wikimedia.org/wikipedi...pole_motor.jpg


Butcher,
Our aquarium magnetic pumps (not iwaki) use ceramic/magnetic rotors and DO NOT use any artifice to get direction. Their impeller blades have to be "semi-crazy" (please, just remove a impeller and see) to get start without load. By absence of direction inductor their rotor can spin at any direction (if you rotate impeller with finger it will assume any direction that you want).

Dissimilarly DC brushless motors (computer fans) use 3 or 4 four coils, driven by eletronic circuit, to get rigth direction and variable speed control. By this way DC pumps (Laing, CSP, MCP) can use curved blade impeller and, better, curved blade at closed impeller.

Once more, excuse this "journal" and my english language.

Iwaki (several, not all) uses assynchronous AC motors with several windings to distribute magnetic field and to generate direction. This design limits speed by main frequency and has a delay that makes a "slide" from that main frequency.
Usually to get rotation speed higher than main frequency mfgs use brushed motors (hairdryer, kitchen equipment, etc). But this construction generates electrical noise so it is not suitable for computers circuit.
DC brushless motor is the answer to get higher and controlled speed without electrical interference.


....once more, excuse english errors....

Thanks for the info, arivaldo, that explained a lot. Don't worry about your english, btw, I hang out over on the VH forums (Malaysia) every now and again. The whole forum sounds just like a motherboard manual that you know was originally written in Japenese but then translated by a program.

Has anyone actually tested new MAG?
 

Has anyone actually tested the new MAG pumps and has C-Systems started its trade-in program yet? My CSP-750 died yesterday, two days short of 6 months. Is it worth it to upgrade or just buy a DDC?

Wow! It died at 6 months?
I hope my ordered (not received) MAG lives a bit more ( i.e. 6 years).

that would depend on whether you want to do new product testing with the associated bragging rights
or WC the computer
how did your previous pump ventures turn out ?
(jeez Bob, you do know how to piss me off !)

Arivaldo
I am aware of NO sleeve bearing shaft supported impeller that has that kind of longevity
- perhaps the discussed sapphire on ceramic will produce such a solution ??
-> but it will take one hell of a lot more than a 3 mo test to characterize a pump's life-cycle characteristics (longevity)

extravagant claims are nothing new, most products get launched that way

as much seems to get ignored in the quest for better solutions,
I would offer (again) some observations about pumps with shaft supported impellers:
the impeller spins on a fixed shaft with a film of the pumped liquid providing a film
(how effective the implementation is can be observed by looking at the sleeve (impeller bore if not sleeved) and the shaft)
- pumps are shipped with some 'assembly' grease, this contaminates the system - but keeps the impeller from rattling on the shaft; cheap pumps rattle quickly, better ones more slowly

a 'quality' pump of this type will have a directional motor (if AC) and curved impeller vanes for better efficiency, and a larger diameter shaft (a good example is the MCP600/50Z)
- but, if bearings are involved then their noise must be addressed, and the pump noise can only increase as the various parts wear

if higher pressure is desired then a closed impeller may provide superior performance depending on the system configuration, and involve high NPSH levels
- not all 'good' pumps do well under these conditions, shitty pumps fail quickly

but superior marketing trumps product performance - most of the time
and superior marketing will trump reliability every time

I'm aware they are straight bladed impellors and will move either way by pushing with a finger. But that still doesn't prove they can spin in either direction - after all a fan can be spun either direction by hand if it's powered off, but will only spin one way when powered on.
I haven't cut open an AC pump to check the internals, but I would assume they have some means of setting direction, be it shaded pole or otherwise. If they didn't have one the motor would not spin up at all (the whole point of the shaded pole etc. is that if you don't start the field rotating the rotor will not spin at all). Given the rotor design I'd guess they use shaded pole synchronous motors.

then ck into it, you are wrong

Sorry, i wanted to say if you power on regular aquarium mag pumps and shoot impeller it will assume the direction you want, because they have no directional artifice.

Just examine one.

Moving back to closed impeller with DC brushless pumps i think that the problems will be:

- short shaft life
- shaft wear
- quickly dead motors

define 'short life'
shaft wear is not a 'problem' until the impeller starts to rattle
"quickly dead motors" ??

other than C-Systems (which they describe uniformly as shipping and user errors), I'm not aware of any "quickly dead motors"
got some examples ?

Bigfoot: DDC Problems...
http://forums.procooling.com/vbb/showthread.php?t=11332

http://www.cooling-masters.com/forum...ic=1446&st=650

i expect to have at least 2 years without motor death (specially suddenly death).
But most important is reliability. So i prefer that pump slowly start to rattle as a advertisement to pay attention on it.

you have cited instances of a known problem, from mfgn - not design
so the failure rate is ? . . . . . . . . .
and since that problem in known, and fixed, then the failure rate is ? . . . . . .

you will buy whoever's BS you prefer
you have no technical basis for your 'problems'
look for the absolute newest product with the most extravagant claims
de gustibus non disputatus (sp no doubt)

[quote=unregistered]that would depend on whether you want to do new product testing with the associated bragging rights
or WC the computer
how did your previous pump ventures turn out ?
(jeez Bob, you do know how to piss me off !)

Okay, Bill, but in my defense I ordered it in August and got it in October. So there was still a lot of FUD being spread at the time I ordered it. I did listen and my new machine uses a 350 and it's a beauty. No rattles, squeals or vibration. That being said, where can I get one of the new integrated pump/res assemblies? Sidewinder didn't show any on the site yet.

a review sample ?
I DID so like your last review, and how it po'd the anti-numbers crowd

you have a MCP350
you want the res/bracket ? or the whole thing with pump ?

Bill,
I don't do reviews anymore. I'll stick to refereed pubs. The devil IS in the details and I'm sorry if some folks don't want to hear it.

too late, on the way
lol

All right then, Bill. Thank you and I have a 5.5 digit DVM card for pH's 3497 and the vi's to make it go. Maybe a second good turn in turn if he's interested, eh?

aiiii
what a Prince
so what's a MCP655 worth ?

What is it? i'm not understanding...you say i prefer BS?
I have just cited a problem to exemplify what i called "quickly dead motors" so you've got offensive... ...or is it my mistake??

We're exchanging technical information about improvement on WC pumps...

For instance, you have cited "pumped liquid providing a film".
How do you think could it works out?
All actual pumps with sleeved impeller have liquid on shaft.
What is the difference that have you offered?

So please if you could not to disagree with respect, just let me know so i will get out.

Think you are mistaken. How does a manufacturing mistake that deals with the programming of the controlling circuits have anything to do with shaft life, shaft wear and tear, or the lifespan of the motor? Let alone a dc brushless pump design in general. Doesnt sound like it does, to me anyways.

if you choose to equate the C-Systems pump with the Laing DDC, that is your business
I have the total # of failed MCP350s in my office, it is a failure rate below 0.5%
(WAY too high, but the cause is known and corrected - not an on-going problem)
Apple has over 150,000 DDC pumps in service
there are MANY reported failures of C-Systems pumps; they have said 'return rate', nothing on failure rate
how many CSP pumps are is service ?

-> and do note that C-Systems has admitted NO product failures to date; all shipping damage and user error
- compare that with Laing publicly disclosing the problem and replacing the units w/o question

you wish to discuss 12V pumps, fine by me
what is your considered opinion on the MCP650/Laing D4 ? remember, it is a 12V pump too
or your considered opinion on the MCP600/50Z, another 12V pump ?

you do not understand how the lubrication system works, high press to low ('high' pressure fluid bypasses the cut and flows around the backside of the impeller and through the sleeve annulus to the 'low' pressure inlet of the impeller)
perfect film = no wear, not on this planet

we probably have some language difficulties
I respond very literally, you possibly are not using English words with the same precision
you are referred to as an uninformed consumer, you may have bits of info but you cannot make sense of them; leading to decisions based on faulty or incomplete reasoning

the DDC is the ONLY successful WCing pump on the planet, and you would equate it with C-Systems ?
must make the folks at Laing real happy, but good news indeed for C-Systems
got to laugh sometimes

Where did i say that? Are you thinking that i am Dave or Dan?
If DDC is pump's God, so Good, i will buy one, eventually.

Oh, thanks for knowlegde about lubrication system.