Induction Coil Ruhmkorff Coils are wound with highly insulated copper wire impregnated with paraffin wax, input 6-8 V d.c. through two 4 mm socket terminals, with an adjustable trembler system. The spark suppression capacitor is housed in the base. A pair of pointer electrodes with insulated handles for adjustement of the spark gap are provided. Spark Length 10 mm, 25 mm, 50 mm, 75 mm, 100 mm.