Getting Down To Construction

The Secondary Coil

It may be wrong, but this is the way I'm doing it. I will start with the secondary and work backwards. I purchased 10 pounds of #20 Enameled copper magnet wire. I know, from MUCH web research, that the secondary should have about 1000 turns of wire. For small coils the height of the coil should be 5-6 times the diameter, for large coils the height should be only 3 times or so the width. No one has told me why, though. I have to trust all the experience of those before me.

Using AWG wire tables, we find that the diameter is .032" (more with enamel insulation, let's use .036) and that it weighs 3.1 lbs per 1000 feet. I have 10 lbs. so that is 10/3.1*1000 or about 3200 feet.

If I want 1000 turns then the coil will be 1000*.036 or 36 Inches tall. To maintain 3:1 Ratio, the form must be 12" in diameter. The circumference will be C=pi*D or 37.67 inches. This diameter will require 37.67*1000 inches or 3139 Feet of wire.... Hey!

Just for comparison, lets try some other diameters (12" Lucite is EXPENSIVE)

 If we use 11" form then: C=pi*d or 34.6". This will result in 3200'*12"=38,400" This divided by the Circumference is 38400/34.6= 1110 turns (not bad so far) giving us a winding height of 1110*.036 or 40" for a ratio of 3.6 to 1. Still not bad.

If we use a 10" form, the circumference will be 31.4 inches. 38,400/31.4= 1223 turns (using all 3200 feet). This will give us a winding height of 1223*.036 or 44 inched for a ratio of 4.4 to 1