Unknown motor/generator

Thread Starter


Joined Feb 12, 2020
Hi folks
I bought this item on eBay where it was described as a generator and pump among a number of other descriptors.
It is principally sold as a mains water generator that will put out 5V when connected to a running tap.
It is close-coupled to a crude pelton wheel that is only obvious when the cover is removed.
I assumed that if I applied 5V to the leads, it would motor, but it doesn't.
Could someone tell me what they think this motor is and is there any simple way to make it run?
Also, what is the small board doing?



Joined Feb 20, 2016
It looks like a generator to me, not a motor.
The coils are connected to a 3 phase bridge rectifier, capacitor and maybe a zener to prevent over volts.
It will not run as a motor.


Joined Jul 18, 2013
Agree, a 3ph generator, there must be a P.M. in the rotor, it could be ran as a 3 phase motor but would need a suitable commutation driver, similar to RC outrunner motors.
Not the way it is right now.


Joined Jun 22, 2012
Like you said it's a 3 phase generator with bridge rectifier and smoothing capacitors...run it under the tap and measure the voltage...


Joined Mar 3, 2014
Is it from a water meter?
Ours sends the water reading in to the water company wirelessly but it has no power supply


Joined Sep 30, 2009
Looks like what my old water softener used to determine when to recharge. It measured the flow through the softener instead of a timer. Was supposed to make the salt last longer.


Joined Sep 11, 2014
Hi John,

Had it been a 5 V brush DC generator, it would have worked as a DC motor, on application of 5 V DC, .

But it's a 3 phase alternator, with a permanent magnet rotor, feeding a 3 phase bridge rectifier to obtain the 5 V DC output.

However, it would work as a motor should the rectifier board be replaced by a brushless DC motor driver.




Joined Jan 23, 2018
What you have is an ALTERNATOR with external rectifier diodes. It is not possible to make it motor by feeding a DC voltage anywhere. It is a cute device and it may work for charging a cell phone battery, but it is not a very high powered device.

Thread Starter


Joined Feb 12, 2020
Thanks for the informative responses, folks, I wonder if someone could draw me or show me a schematic of the alternator, don't worry about the board.
It's not from a water meter, probably just a gimmick, like the radial engine that had magnets reciprocating in radially arranged coils, a distributor and all magnets connected to a conrod turning a shaft. Very cute but apparently atrociously inefficient. The video showed a speeded up manufacture of this gimmick on a small lathe.

Unfortunately, I happen to have a few brushed DC motor speed controllers.
So if'n I wants this thing to pump, I should find a small brushless controller.

What I am doing is building a model of a "perfect" British canal boat.
If I were 50 years younger, I would move to England and build me a full sized boat to live on.
I want it to be aquajet powered so I need some sort of pump amidships. I've seen these tiny motors around 1/4" diameter
called micro coreless motors which I could mount inside a pipe from stem to stern and attach a propeller.
Unfortunately, they run at very high rpm, so perhaps a geared version. What would these tiny coreless motors perform at slower speeds. I guess "suck it and see" is the apt maxim.


Joined Sep 17, 2013
What I am doing is building a model of a "perfect" British canal boat.
I want it to be aquajet powered
AFAIK, no British canal boats are aquajet powered, perhaps because of problems with weed and debris?
A small geared motor would be better than one of those tiny coreless ones. How will you waterproof it?


Joined Sep 11, 2014
Hi John,

Here's a 3-phase alternator schematic.


Star connection is shown with the other option being delta.


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Joined Oct 29, 2013
These days if you can think it, someone has probably made it and it's for sale. There are a number of proper boat jet drives for RC toys for sale, google is your friend. Here's one example, I don't know if these are good or not, but you get the idea:


My guess is you'll get better performance from something purpose built, than by trying to adapt something that was originally intended for a different purpose.
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