The last part of construction is the forming and installation of copper washers in the space between the ends of the inner and outer magnet cores. Specifications of the washers are in Detail D . These copper washers are secured with flathead brass wood screws driven into the inner core. Counter sink the screws into the outside washer, and fill any excess space between the washers and the inner coil with slices of wood or cardboard so the last washer is flush with the inner and outer cores. Do not substitute any other metal in place of the copper washers.
Heavy current induced by the washers require that they be made of extremely low resistance metal.
The current drawn from the line is about 4 amperes, while the currents flowing between terminals 1 and 2 and terminals 3 and 4, respectively, are 18.5 amperes and 9 amperes. This hookup results in a more powerful magnet than the hookups in Schematics A or B . The maximum magnetic pull is obtained with the series-resonant circuit illustrated in Schematic D . The 80-uf capacitance specified in Schematics C and D is built up by paralleling several smaller capacitors. These must be of the non-electrolytic type with ratings of at least 250 volts if connected as in Schematic C , or 600 volts if connected as in Schematic D .