Induction Coil Construction
ULF Induction Coil Core Takes Shape! The core is constructed of 1/8 " thick iron flat stock. Each length is individually sprayed with 3M adhesive and then wrapped with packing tape. Each insulated piece is again sprayed with adhesive and assembled per the drawing below. The final core assembly was then wrapped with 3M electrical tape and sprayed with polyurethane forming a very rigid and secure core.
Coil Form
I must admit the winding of the coil on the form was very tedious and time consuming. 7.38 miles of # 28 magnet wire was consumed. " 19.6 lbs." Approximately 78,000 turns were wound on the form. The final resistance of the coil was measured to be approximately 2.9K-ohms. The wound coil was wrapped with 3M 10 mil. tape and coated with polyurethane. The laminated iron core was then inserted through the inside of the coil form with approximately 8 inches protruding from the ends. The entire assembly was inserted into the final housing which consists of 3 inch PVC drain pipe with end caps. Once the caps were glued in place two small holes were bored into the 3 inch pipe and polyurethane foam sprayed internally until the pipe was full. This adds strength to the assembly making transportation to remote locations easier without the worry of too much stress being applied to the coil and form. Electrostatic shielding was added by wrapping one turn of aluminum foil " 20 mil." around the 3 " PVC pipe. Care must be taken to insulate the ends as not to create a shorted turn. The shield was then wrapped with 20 mil. electrical tape and coated with polyurethane. The shield electrically is connected to the ground site of the Preamp/Signal conditioner input. Final weight of the coil and housing is approximately 50 lbs.
Complete Assembly
