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#1
12/01/2006, 10:02 AM
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maxi jet dc
can a maxijet be converted to dc?
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#4
12/02/2006, 09:29 AM
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thanks dan. i tried it anyways and you where right.
could only get it to jump once counter clockwise and then by reversing the polarity once clockwise. |
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#5
12/02/2006, 10:52 AM
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what kind of motor is the maxi jet?
is it a permenant magnet synchronis motor? Last edited by douggiestyle; 12/02/2006 at 11:18 AM. |
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#6
12/03/2006, 12:27 PM
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la la la
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#7
12/03/2006, 02:29 PM
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guessing it to be just a basic shaded pole motor. not sure if it would be synchronous or induction...my guess would be induction. guess I could pull a broken one apart sometime to see.
__________________
"Those who would give up essential liberty, to purchase a little temporary safety, deserve neither liberty nor safety." |
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#8
12/03/2006, 04:55 PM
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shaded pole.... which is a form of iinduction motor...
However the "induction motor" you guys are thinking of (like your table saw motor) is a bit different and would cost WAY To much. Tear one apart and you will find that it has 2 poles wrapped with 1 coil. 1 pole per half of the motor. The impellor is the permanent magnet "stator". Your table saw has several poles and usually a startup winding and 1 or more run windings. That is why [the powerheads] they chatter so bad on startup. The poles roate faster than the magnet can keep up. The reason the shaft is loose on the magnet or impeller is simply to allow the magnet to start turning and overcome the water resistance that would otherwise prevent it from turning and turn it into a vibrator. Bean Last edited by BeanAnimal; 12/03/2006 at 05:10 PM. |
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#10
12/05/2006, 08:52 AM
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odd shape for a vibrator. to each his (or her) own.
 so the ph speed is controlled by the the frequency of the ac current? so its more of a single phase ac synchronous? anyone familiar with a relay starter? not sure if im stating that correctly. |
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#11
12/05/2006, 09:38 AM
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Gutter minds....
The power heads are very simple single phase shaded pole motors. That makes them induction motors... and likely synchronous at no load. Relay starter? Please elaborate and we can fill in the gaps. |
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#12
12/05/2006, 11:45 AM
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its a starter relay. used for smaller motors. i was thinking it sets the direction but it only helps get a motor started.
so the frequency doesnt set the speed? so to control the speed would be a rheostat? |
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#13
12/05/2006, 12:30 PM
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Yes the frequency sets the speed. The AC waveform switches poles 60 times a second. Each time the poles change the megnetic field around the stator switches.
When you hooked the motor to DC you created a magnetic field that never switched poles. One side of the coild was N and the other S. The stator spun 1/2 turn to align with those poles. If you put a double pole switch and manually flipped it and changed the poles back and forth.. the motor would spin. Ahhhh! You would be providing the motor with AC current A DC motor (universal motor) does this by wrapping the STATOR with coils of wire (at least 2) that are not connected to each other. They are connected to the DC currnet by means of brushes. Each tome the STATOR makes a half turn, it breaks contact with the DC on one side and makes contact with the other brush that has it's polarity reveresed. This is the same as you "flipping the switch". Did I explain that well enough for you to understand? Speed control gets somewhat complicated with AC motors. It depends on the type of motor AND the torque needed to keep the motor running. Vague... well it is a broad subject. |
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#14
12/05/2006, 01:16 PM
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thanks. yeah i understood all that. i was reading the mj mod site and its inferred there that the mj could run off dc, or at least that was the way i read it. yeah i figured it out the moment i hooked it up to dc power. thats why i assumed it to be a synchronus motor with speed dependent on the line frequency. but if its a shade pole motor... most of the small fans in range hoods are and their speed is controlled with a rheostat.
i guess what im getting around to is controlling the speed of a ph. im am currently looking at using an aqua clear ph into a tunze style mod. i like the way i can more easily convert the aquaclear over the mj. (ive been looking at various ph and aqua clear is by far the simpilist to modify) so anyways im looking at not cycling on and off the ph but instead lowering and raising their speed to controll flow. im guessing that by controlling the voltage you are not so much controlling the speed of the motor but its torque which would affect how quickly the stator will move? also i was looking for a way to controll its direction to eliminate the little tab that stops the prop and causes it to reverse. but i guess its a moot point because if i use a rheostat to raise and lower flow then the motor would rarely shut off there by eliminating the constant use of the tab. |
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#15
12/05/2006, 01:22 PM
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the man tells his doctor
"i was cleaning the tank and i slipped and fell and it just went up in there" the vibarting ph..... ha ha ha....... |
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#16
12/05/2006, 02:00 PM
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The small fans in range hoods and fireplace blowers etc... do not have torque problems associated with speed control and the rheostat
They also do not have heat problems per say. Yes... when you change the voltage on that type of motor, you are causing a loss of torque and the motor slips and produces heat instead of angular movement. You may not have a lot of luck trying to use voltage... but it is worth a try. I suppose the best answer is to come up with a DC motor to drive your prop... that means a sealed shaft and wear parts. Bean |
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#17
12/05/2006, 04:48 PM
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Well, tunze turbelle and stream pumps are DC for speed control, but yeah... look at the price... ouch! They are magnetic drive as well though, no sealed shaft. I wish more companies made DC powerheads... wavemakers would be sooo much easier to use/make then.
__________________
"If at first, the idea is not absurd, then there is no hope for it" -Al Einstein |
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#18
12/05/2006, 05:01 PM
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quote:A DC motor (universal motor) does this by wrapping the STATOR with coils of wire (at least 2) that are not connected to each other. They are connected to the DC currnet by means of brushes.:quote
rc car motors went brushless a while back now, i always thought one could be used to make a ph, if its encased in epoxy.. seems like a heck of a project tho... fwiw |
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#19
12/05/2006, 05:10 PM
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Quote:
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#20
12/05/2006, 05:10 PM
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hahn... they don't have a sealed shaft, but they are also not simple motors or transmissions that you are going to DIY. MY comments were in regards to finding a small DC motor and DIYing a unit out of it.
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#21
12/05/2006, 05:16 PM
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oh yeah, sure... I got you on that. I just wish more companies would make DC powerheads. Right now, Tunze seems to have the monopoly, and that means $$$.
I dont know... you are right that a 'simple' DIY would require a shaft driven motor and waterproof bearing of some sort, but if someone wanted to, they could get into it, making their own DC magnetic-shaft motor from scratch, and encase it in acrylic/epoxy. It might not even be that hard... just winding copper and soldering. Some precision work, and knowing what you are doing... but not too bad. The hard part would be the shaft/impeller assembly, but with any luck, these parts could be taken from an AC pump. Or, yeah... for larger pumps, you could take the housing from an Iwaki (like weatherson did for his pre-oceansmotions valve unit) and get a large DC motor for it... the impeller and shaft just being borrowed from the AC counterpart... you know... a motor swap.
__________________
"If at first, the idea is not absurd, then there is no hope for it" -Al Einstein |
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#22
12/05/2006, 05:18 PM
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A brushless DC motor IS NOT A DC MOTOR
It is really an AC motor with a controller that takes DC voltage and pulses it between 2 or more poles on the motor.Yes hobby car motors may be good candidates... the 2 pole variety spin very fast (though they don't have much torque). The more poles, the slower the motor, but the more torque it will produce. I can't see this going too far as you gusy are going to be looking at some pretty fancy fabrication and at that point the Tunze starts to look pretty cheap. Bean |
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#23
12/05/2006, 05:22 PM
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It may not be a true DC motor, but it still allows you to have extra poles for torque, and the ability to manipluate the speed.... thats whats most important here.
__________________
"If at first, the idea is not absurd, then there is no hope for it" -Al Einstein |
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#24
12/05/2006, 06:35 PM
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why not builed a sliding inlet shutter over top of the slits cut for the inlet. Seems a lot simpler and would work.
Not externally adjustable is the downside but if you just want a set rate of flow...
__________________
"Those who would give up essential liberty, to purchase a little temporary safety, deserve neither liberty nor safety." Last edited by BruiseAndy; 12/05/2006 at 06:52 PM. |
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#25
12/05/2006, 07:03 PM
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well, right, the whole point is that we want something that can be run on a conroller for current simulation.
__________________
"If at first, the idea is not absurd, then there is no hope for it" -Al Einstein |
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