If that is in response to my comment, the question raised was whether shaded pole motors have permanent magnets as the rotating piece. Can you give an example of one? Thanks. John

 

I can't give a definite example but I'm pretty sure mechanicla mains clocks us shaded pole synchronous motors.

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not really an electrical solution, but have you considered installing a relief valve to regulate the flow rate instead of the motor speed. much simpler! just adjust to the flow rate you want and the excess flow will dump to whatever tank you are pumping from w/o an increase in pressure

 

FWIW,
most air pumps have a motor, but it isn't a rotational motor, rather, it is a sort of linear one, in which a magnet moves back and forth between two coils, moving the bellows as it goes.

 

Similar to 480threephases' suggestion, dont look for an electrical solution, but look for an hydraulic solution.

I assume that you dont want to be constantly varying the flowrate, so just install a bypass valve around the pump. ie a tee piece on the input to the pump connects to a valve which in turn connects to a tee piece in the output line of the pump.

When the bypass valve is fully closed the pump will deliver full flowrate, when the valve is fully open, the pump will deliver very little, it will just be recycling.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

 

the broucher does explain your solution already

Instructions:
Water flow decreases when the Venturi feature is used. If no air is desired or if you prefer to use the Maxi-Jet with the Prefilter Grid, do not install the Air Tube. Cover the Venturi opening with the enclosed clear-plastic Venturi Plug.

did you try it also without pluging the ventury opening so that it sucks water instead of air? and if you did what was the result?

as for the price of the pump all efforts to reduce the flow rate electricaly are probably more expencive than looking for a new and somewhat smaller version

Robert-Jan

 

fish Tank Supplies > Fish Tank Pump & Power Head > Fish Tank Power Head > Maxi-Jet & Mini-Jet Powerheads



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with these prices there is no way i would consider to modify a pump flow
i would put my efford in trying to change the pump over at the store for one of those adjustible ones with a lower flow rate

i thing if you just change over and don't ask for the price difference that they don't make to much trouble and otherwise you just buy one it's less than $20 (i bett your fish are more expensive)