[SEL] Low tension coils

[Elden DuRand]

Ron & Steve:

I think I didn't give enough information before.  Referring to my 1908 Electrical Engineer's Handbook, I have the following data for annealed copper wire:

16 gauge wire - 249.4 ft/Ohm
18 gauge wire - 156.9 ft/Ohm
20 gauge wire - 98.66 ft/Ohm
22 gauge wire - 62.05 ft/Ohm

For a 6 Volt coil to draw 2 Amps, you'd need 3 Ohms or:

16 gauge wire - 750 ft
18 gauge wire - 471 ft
20 gauge wire - 297 ft
22 gauge wire - 189 ft

For a 12 Volt coil to draw 2 Amps, you'd need 6 Ohms or:

16 gauge wire - 1,500 ft
18 gauge wire -    942 ft
20 gauge wire -    594 ft
22 gauge wire -    378 ft

Simple, eh?  Makes me want to go out and wind a few coils!

Other than measuring the length of the wire before starting winding, you could select your wire gauge and make a guess at the size of bobbin you'd need for the requisite amount of wire (adding some just for yucks).  Then, after winding what you -think- is enough, hook one lead of your trusty Ohmmeter to the "starting" end then scrape just a minute amound of insulation off the wire and measure.  From that, you should be able to tell how close you are.

To fix the insulation, you could either fold a tiny sliver of tissue paper around the wire then wind it onto the winding or you could give it a shot of either lacquer or "glyptol" to insulate the spot.

Take care - Elden
edurand at iglou.com
http://www.oldengine.org/members/durand 

> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com]On
>  Behalf Of Steve
> Royster
> Sent: Friday, November 17, 2006 12:58 PM
> To: sel at lists.stationary-engine.com
> Subject: RE: [SEL] Low tension coils
> 
> 
> How can you check the proper resistance after 
> winding the coil,  but before 
> you cut the roll of wire you are winding it from? 
>  Thanks, Steve
> 
> 
> >From: "Elden DuRand" <edurand at iglou.com>
> >Reply-To: The SEL email discussion list 
> <sel at lists.stationary-engine.com>
> >To: "The SEL email discussion list" 
> <sel at lists.stationary-engine.com>
> >Subject: RE: [SEL] Low tension coils
> >Date: Thu, 16 Nov 2006 18:54:40 -0600
> >
> >Ron:
> >
> >I think around 18 to 20 gauge would work well.  
> Wind enough wire on the 
> >core to get enough resistance for it to draw a 
> couple of amps at whatever 
> >voltage you plan to run it at.
> >
> >Take care - Elden DuRand
> >edurand at iglou.com
> >http://www.oldengine.org/members/durand
> >
> > > -----Original Message-----
> > > From: sel-bounces at lists.stationary-engine.com
> > > [mailto:sel-bounces at lists.stationary-engine.com]On
> > >  Behalf Of
> > > rdhaskell at juno.com
> > > Sent: Thursday, November 16, 2006 04:48 PM
> > > To: sel at lists.stationary-engine.com
> > > Subject: [SEL] Low tension coils
> > >
> > >
> > > Hi all.
> > > I have a chance to pickup copper magnet wire in
> > > various diameters for
> > > scrap price, what would be a good size for 
> winding coils?
> > > Thanks.
> > >
> > > Ron Haskell