Fun with an Old Spark Coil (Jan, 1932)
Fun with an Old Spark Coil
By RAYMOND B. WAlLES
ALTHOUGH producing a spark only about three-eighths of an inch in length, an auto (Ford) spark coil can be made to produce a brilliant stream of sparks, about two inches in length, by interposing small flakes of graphite throughout the gap. This is easily accomplished by dusting flake graphite on a tacky varnish card through which are fitted two machine bolts or binding posts for contact with the secondary terminals.
Trick cigarette papers can be made, by holding the book type of papers in the spark stream of a coil. The sparks will perforate the paper; so that a cigarette rolled with it will not draw no matter how hard it is puffed.
“Jacob’s ladder” operates well on a larger-size spark coil. This “ladder” consists of two stretched upright wires, spaced about half an inch apart at the bottom, and about an inch apart at the top. When they are connected to the secondary side of a coil, sparks will run up the wires, forming a ladder of fire.
A luminous character cut from metal foil can be made to give a brush discharge which is extremely interesting and pretty. Three sheets of glass are taken and, between the bottom and middle glasses, a sheet of tin foil is placed and connected with one secondary terminal. The character, say a letter or club insignia cut from tin foil, is placed between the middle and the third sheet of glass and connected to the other secondary terminal. This set-up works well on a small auto coil.
If an upright metal plate, about eight inches, is mounted on one secondary terminal and the coil operated, a neon lamp will light when placed as much as eight inches from the coil.