Aluminium Muliti-blade Rotor problem

Anybody know why an aluminium multi-blade rotor would effect the turbines electronics. I cant work out what is going on, the turbine works fine until the rotor is attached, then nothing.. The electrics in my circuit consist of a dynohub, BR, Relay switch, capacitors and a diode.

If you turn the rotor by hand you can get power and hear the relay switch on, but as soon as the rotor is added, even the small 5v relay does not switch on. Any ideas?

Hey Danny,

Welcome to GotWind!

By "rotor", I assume you mean the propeller rotor? I only ask because you state "the turbine works fine until the rotor is attached", and I assume here you mean that the dynohub works fine until you attach the rotor & blades to it?

Assuming my assumptions are correct (lol), there is no good reason the dynohub would respond differently to a particular type of mechanical input. It should produce X open circuit volts @ Y RPM regardless if it is connected to blades, a bicycle or a hand drill. I will mention that the dynohub is a fairly low output device (1.8W @ 6V).

I am sure Ben will respond, he has built some mini-turbines from dynohubs, and I am sure will provide you some links.

If you post a few pictures, perhaps we can "see" some flaw, but really, it should be pretty straight-forward.

Fish

Its a bit of a mystery to me and I cant see why the multi-blade should effect the circuit either, but it does. At first I thought it must be something to do with the Earth contacts as I think it is necessary to separate the AC circuit from the rectified AC (smoothed DC), but why would the aluminium rotor change anything as the spindle is metal anyway? Hugh Piggott pointed out that turning the spindle by hand may result in more rpm than the multi-blade, but nonetheless the circuit works perfectly if turned at very low speed (i.e 1 revolution per second), but not at all once the blades are attached and spinning at far higher speeds. Will find a picture

Eddy currents across metal rotors can negate your electrical fields.

You can always run a belt from your rotor over to your PMA. I know belt drives have a bad name around the green crowd, but they work.

[Gotwind Ben]

Matt.
Nahh, I can't imagine that ever happening.