Magnetiser: Capacitor-Discharge Magnet Charger with a Wire-Wound Fixture (Janicke, US 3,070,731, 1962)

Feed a line switch from the mains through two fuses, with a pilot lamp. Wire a high-voltage transformer with two primaries, which a high-low switch puts in series or in parallel. Run its centre-tapped secondary to two mercury-vapour rectifier tubes, "or the like", with their own filament transformer, so they charge the energy-storage capacitor. A charging on-off switch with a red lamp switches the high-voltage side. A meter with multiplier resistors across the capacitor shows its voltage. Ours: toggle switches, neon lamps, a moving-coil meter. Not given: any voltage or value.

Put a thermal time-delay relay before the charging switch: about thirty seconds after switch-on it energises a control relay, which feeds the charging switch and holds itself on. A third contact of the control relay lifts a bleeder resistor off the capacitor while the charger runs. When the charger is shut down the relay drops out and the bleeder drains the dangerous high-voltage charge from the capacitor.

Put an ignitron in the discharge path of the storage capacitor, as its switch. The meter's multiplier resistors also form a divider that charges a small firing capacitor. Pressing the push button discharges the firing capacitor through a small limiting resistor into the ignitron's igniter, and the ignitron conducts. Not given: the firing capacitor's type and value.

Weld a hollow cylindrical shell onto a base plate on levelling legs, both of magnetic material, to make a pot. Cut slots through the shell and the base plate so they cannot act as a shorted single-turn winding. Set the coil inside the shell in potting compound, with ring-shaped end pieces and a hollow cylindrical core in it. Hinge a square magnetic cover on a post beside the shell, held by a collar and set screw, with a handle. An L-shaped plate on the cover closes a switch in the igniter circuit only when the cover is shut. Wire the coil between the storage capacitor and the ignitron anode. Ours: mild steel, enamelled copper wire, casting epoxy. Not given: sizes, turns.

Put the magnet inside the core. Fill most of the air gap between it and the base plate and cover with soft iron, but leave a small gap near the cover, or the cover will be hard to swing open afterwards. Lay insulating material about 1/16 inch thick on top of the magnet. Close the cover, which arms the igniter switch, charge the capacitor, and press the button: one pulse magnetises it. Ours: wrought iron for the soft iron.