Muller Dynamo

[baroutologos]

Romero has made a calculation mistake as has been pointed out several times in this thread. But if you got thicker wire it will yield more current.
You might wanna re-calculate your coil dimensions though with 0.375mm instead of 0.875mm  though before you start to wind if you got 7 strands of 0.125mm wire.

Hey Xeno,

Gathering parts for my replica, i stumbled at wire also. yes indeed Romero gave the 0.125*7  enameled wire specs with ref code, but as you pointed out this makes a 0.4mm diam more or less. Romero also said that his wire was 0.6 mm diam or so in his forum and perhaps he mentioned the 0.8mm figure.

I suppose he was not critical about wire's diam but he was to be it a Litz one (strands isolated). By the way, in my eyes from his rotor pics, the wire seems bigger than 0.375mm, much closer to 0.6mm or 0.8mm

Anyway, i will stick to the ref code he gave. I do not believe that the thinner and somehow more resistance litz wire will considerably affect the device at those power levels for 7 pick up coils.

[Magluvin]

Also this vid showing the bearing not installed in the rotor.

http://www.youtube.com/watch?v=iSTfFIetYPY

Ceramics are not cheap.  But the hobby bearings can give great results if treated properly.  The graphite has to be worked in as if to crush it in while working it in under pressure.

The bearing will sound a bit sandy and noisy as you work in the graphite.
But you will be very happy with the results. ;]

Mags

[Mem]

I think that is the best bearing for skating.  And maybe a vertical rotor but will it handle high RPM?   I read that skate bearings may not be best though for a horizontal rotor like this build Romero did.  A thrust bearing was mentioned as a good choice.  I also think any VCR head bearings as tysb3 mentioned would be a very good choice.  You can probably pick up a used VCR for a lot less than the cost of one of those skate bearings and then you can scavenge a pile of other good electronic parts too

I agree with you, VCR head bearings are quite good for this project, plus their low friction and it's free to get it. All it will take 30 min. of labor to salvage it.  Mounting it here is a drawing for you guys.

[Thaelin]

   If you use vcr heads, be sure to add a keeper of some kind to the end shaft so it will not lift up. Side travel for the rotor will allow hitting the coils. Depends on how big a rotor you are running too. I cant use these as my mags are 3/4"X3/4" and the shaft is 1/2" with a 12" rotor.

thay

[toranarod]

Hey Xeno,

Gathering parts for my replica, i stumbled at wire also. yes indeed Romero gave the 0.125*7  enameled wire specs with ref code, but as you pointed out this makes a 0.4mm diam more or less. Romero also said that his wire was 0.6 mm diam or so in his forum and perhaps he mentioned the 0.8mm figure.

I suppose he was not critical about wire's diam but he was to be it a Litz one (strands isolated). By the way, in my eyes from his rotor pics, the wire seems bigger than 0.375mm, much closer to 0.6mm or 0.8mm

Anyway, i will stick to the ref code he gave. I do not believe that the thinner and somehow more resistance litz wire will considerably affect the device at those power levels for 7 pick up coils.

I have been going over the wire figure's  We are all wondering about the Dia of the wire and keep coming up with the wrong answer.
the other point is we also cannot figure out the voltage is low if we go by his coil specifications.
I have been going over the figures time and time again.  What if its the turns that are wrong.
the coil dimension and the voltage out and the wire used would imply the turns are wrong.  I calculate the tunes to be around the 700 mark to fill the coils how they look in the photo's if he used 7 X .125.