How to install and tie together magnet wire coils

[aidrenegade]

  After a bit of a break away from this project today has proved a disaster! So where did I go wrong with this coil idea? It was kind of inspired by the low lens drag video:

http://www.youtube.com/embed/bfgzfl69Q20

My coil wont produce any voltage! I thought that winding it together as per this photobucket slideshow would reduce lenz drag:
http://s1272.photobucket.com/user/wayfoward/slideshow/coil

Note how the mild steel bar I used as a core does not rotate. Instead I wound the 10 rolls of enamel wire around it in a clock wise direction, overlapping previous layers continually moving in a clockwise direction as indicated in the first 11 photos by the lettered coil rolls. I've tried both DC and AC configurations of my 35kg pull magnets. They are a bit further apart so I was expecting to need higher revolutions compared to my old setup. Not a single volt at 500rpm was a complete suprise! I've checked all tails to make sure there are no continuity breaks in the enamel wire.

[gyulasun]

Hi,

I am afraid you have managed to assemble a setup by "overcombining" some pieces of information. I mean the links I referred to do not clearly indicate a continuous ring core, where-ever such seemingly continuous rings are shown with several coils on their outside, we do not really know for certain whether the magnetic core is a continuous ring (cut at say one place only, like you show) or it is made from short pieces of cores with air gaps inbetween?
Another issue may be the mild steel bar you use as a core: how it performs really as a core when either you DC pulse it or feed with AC current?  I think of eddy current losses. 

Anyway I cannot imagine that the core shape as you would like to use it as a common core for each coil could perform correctly, I can only think of individual (as short as the coils) cores for each coil, with air gaps between the facing ends... that way the magnetic poles in each short core could develop and change in strength when a magnet passes by so there must be a better chance for induction. With a continuous long ring like core this is unlikely to develop, this is what I think.

I may sound to suggest chopping up your mild steel core for coil-long pieces...  so if you do not mind doing that, just do it. Before that, have you measured the inductance of the coils individually with an L meter? If there is a short then the inductance is small hence no much chance for receiving induced output voltage. Of course I speculate you might have a short.

rgds, Gyula

[aidrenegade]

Quote: "Before that, have you measured the inductance of the coils individually with an L meter? If there is a short then the inductance is small hence no much chance for receiving induced output voltage. Of course I speculate you might have a short."

I have a capacitance meter although I've never used it. Looking online I see dual capacitance / inductance meters for sale. What is the differance? Can I work out the inductance with a reading from my capacitance meter (needs a battery first) or should I buy an inductance meter for the job.

[gyulasun]

Hi,

Watching again your mild steel core, how did you fasten its ends to form the ring? Did it become a continuous metal ring with no air gap? In your 1st picture there is the bare long rod bended and in your 2nd picture I can see a thicker ring already in a full circle, covered with black tape?

And how did you try to induce voltage with the magnets: how you moved or rotated the magnets with respect to the ring core? Could you show a picture on the magnets arrangement? It would help me to ponder on further...

Well, if you wish to make several coils in your tinkering hobby on the long run, then an L meter or LC meter would be worth investing. See these choices:

http://www.ebay.co.uk/itm/UK-LCR-RCL-INDUCTANCE-Capacitance-Resistance-Meter-/140968592347?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item20d26203db

http://www.ebay.co.uk/itm/L-C-Inductance-Capacitance-Multimeter-Meter-LC200A-Tool-DC-USB-Cable-/160862532321?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item25742772e1

The first type is probably the same as the XC-4070L for which there is a user manual online: http://pikirsa.wordpress.com/2013/07/01/lcr-newcason-xc4070l-user-manual/  and it turns out the measuring frequency for the coils is 100 Hz which is low enough.

The second type (LC-200A) has two measuring frequencies: around 500 kHz and at around 500 Hz which is very good (i.e. it uses two frequencies and the actual frequency can be seen on the display with function button pressed) but for using a coil at or lower than 40-50 Hz, especially with a core working at 50 Hz or so (and being lossy at higher frequencies),  it is not a good idea to measure it at even 500 Hz, it will have a more or less modified value at the lower frequencies. Nevertheless, the wider measuring ranges and precision of the LC-200A are more attractive than that of the CA-4050L (with XN- or BN- prefix also probably the same 4070L type), albeit this latter measures inductances at 100 Hz.
(here is an attractive looking meter http://www.ebay.co.uk/itm/UT602-UNI-T-Modern-Inductance-Capacitance-Meter-Uni-Trend-/290787278384  and its measuring frequency is 1 kHz up to the 2 Henry (from 2 mH) range and 100 Hz only in the 20 Henry range)

Regarding your present C meter, my question is whether its measuring frequency is specified in the user manual or could be figured out from the web by searching for it by type? IF there is no any data on this, do you have a frequency meter, able to measure around 100 Hz to a few kHz? like a digital multimeter often has such feature or you have access to an oscilloscope?   

The reason I ask is that probably by connecting a known good quality capacitor in series with an unknown coil you could see the modified capacitor value on the C meter and doing some calculations you could arrive at the coil inductance but for this you would need the exact measuring frequency of the meter with that series LC reactance combination.

Gyula

[aidrenegade]

Here's an online pdf user manual for my capacitance meter: http://www.peakelec.co.uk/resources/esr70_userguide_en.pdf

The last coil has now been broken down and wound back onto the individual reels (about 35m of 1mm wire each). I will use each reel as a coil. I was hoping that by measuring the inductance of each reel and unwinding reels as required to give each one the same inductance they would then produce about the same voltage at a given rpm, not more than 600rpm. I just need the cheapest meter good enough to do this. When I rebuild my magnet assy with 10 reels and 10 pairs of magnets I will us a dc NS, NS, NS etc arrangement and aim for a direct dc output without need of the joule thieves.

Looking again at the low lenz drag video:http://youtu.be/bfgzfl69Q20 I notice that the air gaps are about the same length as each coil (or reel). I will try 10 coils first with small air gaps between coils and if it doesn't work I'll reduce the number of magnets / coils and try to reproduce a simular assy to his. I've yet to get hold of an iron bar of about 15mm dia to make cores for the reels.