STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[Omega_0]

I agree with one of the posts above that many builders don't bother to measure the input and output energy. I've rarely seen any thorough measurements done, and usually its a spinny thing and a glowing LED at most.

I think many do measure outputs and try to close the loop but don't post their results because, clearly, they are not OU and it discourages others, so they keep the enthusiasm up. This is both good and bad, and I leave it to builders to decide.

Anyway, I'm thankful to someone who mentioned de Prony's method for measuring output. I believe its the simplest method for such projects. This picture shows a simple Prony brake with needed equation.

I guess the brake should be made out of plastic or wood and need not be perfect. The red wheel here is an extra wheel fixed on the shaft. You simply need to tighten it till the arm exactly levels without support or stoppers, at which point the weights hanging from it are balancing the torque. Choose any convenient length and weights.

You must take many readings, at same input and at various other input current levels and duty cycles and magnet strengths and core materials and coil turns etc etc. Plot a graph and see if there is a sweet spot. I know this is hard work, but there is no point if you are not interested in making the setup OU.

Input is as usual P(in) = Vpeak* Ipeak * Ton/(Ton+Toff)   Watts.
Where Ton and Toff are pulse on and off times.

[neptune]

@Omega O . Your post re the Prony brake was very informative . Just a couple of practical points .  First the arm needs to be fitted with stationary safety stops to limit its motion to say 20 degrees either side of horizontal . For initial tests , a suitable " fish scale type spring weighing device {calibrated spring"] might be handier than weights .Finally , if your rotor shaft is vertical , the string suspending the weight needs to be run over a pulley .

[Omega_0]

neptune, thanks for your suggestions.

More on measurements:
Of course, one can argue that hooking up a generator and measuring its output should be more convenient. Well, if you trust your generator, sure, go ahead, and if its really OU, loop it back.
In practice, I've seen that all gens are made for specific purposes, for specific RPMs/torques and are most efficient only for a narrow range of loads (i.e. it must match the load to be 90%+ efficient). So if the gen is not suitable and the OU is tiny, you will surely miss it.
With mechanical methods you are always sure.

So lets take an example:
Say, your setup is taking 10 W at the input and you hang 100 gram at 50 cm on the arm and brake it till it reaches a steady RPM and is not trying to drag the arm along. To be OU -

P(out) > P(in)
or (100/1000)*(50/100)*RPM > 10
or RPM > 200

If RPM in this example is measured above 200, then you have some hope, else note it all, change stuff, rinse and repeat, like a good scientist

[petersone]

Hi powercat
Very good and instructive vids,thanks,but one question that you or others may be able to answer,if one had ideally set up pulse motor with GENUENE zero cemf,would it guarantee ou?
peter

[powercat]

Hi peter
To answer your question, I don't know yet, I hope so as I believe in OU, a lot of people have built motors  with no attempt to generate power, but it is early days.
Why did Steron  have a gap in their demonstration, maybe they hope someone else will figure out
the OU part for them.
I was thinking about those V gate magnet motors, maybe it'll help clear the sticky spot, saving  power as it only needs to fire once every rotation, hmmmm

Anyway enough from me here is another new video from TK
Orbette 10: Quivering, and Low Voltage Operation
http://www.youtube.com/watch?v=_PiOUFzcaCc

Here is an idea for a big magnet bearing, useful for those considering a big rotor
http://www.youtube.com/watch?v=PfZUmbxzUM4&feature=related

cat