[SEL] Low tension coils

[Elden DuRand]

Dave:

I may have confused the listings.  There are three tables.  The first one is feet per Ohm for four gauges of wire.  Just multiply the number of Ohms you are looking for by the ft/Ohm number of the wire of choice.

The second and third tables are for the amount of wire to draw 2 Amps.  The second table is calculated using a 6-Volt battery.  The third table is calculated using a 12-Volt battery.

If you want something other than 2 Amps at either 6 or 12 Volts, use the first table.  Let's say you want a coil to draw 5 Amps at 8 Volts.  Use Ohm's law to find the resistance you need to get this result.  Since R-E/I, divide the voltage (8 Volts) by the current (5 Amps).  This gives 1.6 Ohms.

Now, let's say you have a spool of 18 gauge wire laying around that you want to wind the coil with.  To find the length of wire needed, multiply the resistance wanted (1.6 Ohms) by the feet/Ohm from the table (156.9) to get 251.04 feet of 18 gauge wire.  

How'm I a-doin/?

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 Dave Croft
> Sent: Friday, November 17, 2006 06:40 PM
> To: The SEL email discussion list
> Subject: Re: [SEL] Low tension coils

> > 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
> 
> Hi Eldon, you don't give the supply voltage so
> I cannot check out your currents.
> Dave Croft
> Warrington
> http://oldengine.org/members/croft/homepage
> http://community.webshots.com/user/crftdv
> 
> 
> _______________________________________________
> SEL mailing list
> SEL at lists.stationary-engine.com
> http://www.stationary-engine.com/mailman/listinfo/sel
>