Muller Dynamo

[duff]

LOL !  I agree that RomeroUK was very certain in stating the all North up configuartion in the rotor and I'm sure he was not confused on that matter.  And I agree scopes are fun and fortunately I bought 3 of them when I had money....  although you can certainly find good deals with some effort on fleaBay.

@e2matrix,
Romero states the South pole is facing up...

2 hall sensors. I will take some closer pictures to see them.The side of the rotor has small magnets with south pointing out.

All magnets on the rotor are all pointing same direction, as you look at the device all magnets are with South up. I have never tried to run it upside down because of the dirving circuits but I will try it having it on one side.

However, the following is a little confusing.
It is from Romero's Forum

Re: RomeroUK Work Pictures
« Reply #117 on: April 07, 2011, 01:05:22 PM »
The rotor has 8 magnets all positioned with North on one side and South on the other side.

[neptune]

@Nvisser . A most interesting and informative post . Look at sample 2 . I f we moved the magnets closer together , or indeed a bit too close together , would that not give us the mysterious KROMREY waveform , that looks a bit like a repetition of the letter W ?

[duff]

Regarding magnet spacing I can't argue with anything konehead says since he's miles ahead of most of us in motor building but I do recall Romerouk said (or someone here recently stated Romoerouk said) that for this motor the best spacing between magnets is 2.5 times the diameter of the magnets.

Yes, David70 did state that Romero recomended "at least 2.5 times"

If you measure the current the spacing of the magnets on the rotor you will find they are 3 times the diameter of the magnet.

Also, I'll point out the the pdf of the first page states the rotor is 25cm, however Romero makes a correction and states it is actually 20 cm.

Hi,
I have measured the rotor and it is 20cm, sorry. I had so many changes and I also had a 25cm and a 35 cm rotor in another setup.
Diameter has nothing to do with the results if u space the magnets equally.
...

[baroutologos]

EMdeices said

I think romerouk might have been confused about the rotor magnet polarities he gave us in the beginning.  He did say he played with a few rotors.

From the analysis of the output waveform, we see a rotor modulation and that corresponds to 4 cycles,  so I'm beginning to think the rotor should really have this magnet configuration:   N  S  N  S  N  S  N  S, after all, that's what Bill Muller's dynamo uses.
Romerouk, do you remember what rotors you played with and what polarities they were? 

thanks,
EM

My answers is yes and no.

No. The red line you had on first image corresponds to the blue line to the second image. I think is clear to see. An o-scope will put "left" or "right" the flat area depending the leads connection (at least my scope does that)

yes. Romero's scope shot in a strict comparison to others or mine, has the flat area much flatter and the steep area less steep than i get.
Note, as i explained my observations few pages back, that the biasing magnets can alter that.
In my case the flat area gets flatter, voltage peak increases a bit and the steep area gets steeper. No need to say that again. Perhaps i will make a video someday.

I made my rotor per Romero's specs. 200mm dia, 19mm magnets (10mm thick single ones) 6 mm distance to circumference. (Romero had less i suppose but i need some safety on that ground) 8 magnets in rotor same polarity on side.

I have the impression that minor waveform changes occur with rpm.

@Konehead,

I agree with you concerning the waveforms except the strict magnet physical possition corresponding to wave form
By increasing speed magnetic lag appears. This i have read and i noticed that with rmp the sweet spot of halls changes for giving max efficiency. (a bit)

At least this happens to my setup..

[wattsup]

This explains what you described.

Very nice post but there is something definitely wrong there in frame #3.

In the first two you show only north passing or north and south passing, but regardless of what polarity and what distance between magnets, each magnet passage is producing a full sine wave with the TDC separating each one.

But in the third, the TDC is between each half cycle. That should not be possible regardless of how the magnets are set, close or far, each passage should be one full cycle with TDC in the center of the cycle. Unless what you are saying is that a cycle in fig 3 starts at positive or negative peak with the TDC between the peaks. That seems to be incorrect.

wattsup