Collecting Ring.
In some kinds of generators instead of the commutator a pair of
collecting rings of metal, insulated from the machine and from each
other, are carried on the armature shaft. A brush, q. v., presses on
each, and the circuit terminals connect to these two brushes. Such rings
are employed often on alternating current generators, where the current
does not have to be changed or commuted. Collecting rings with their
brushes are used also where a current has to be communicated to a
revolving coil or circuit as in the magnetic car wheel, the cut of which
is repeated here. The coil of wire surrounding the wheel and rotating
with it has to receive current. This it receives through the two
stationary brushes which press upon two insulated metallic rings,
surrounding the shaft. The terminals of the coil connect one to each
ring. Thus while the coil rotates it constantly receives current, the
brushes being connected to the actuating circuit.
Fig. 105. MAGNETIC CAR WHEEL SHOWING COLLECTING RINGS AND BRUSHES.
Collector.
(a) A name for the brush, q. v., in mechanical electric generators, such
as dynamos, a pair of which collectors or brushes press on the
commutator or collecting rings, and take off the current.
(b) The pointed connections leading to the prime conductor on a static
machine for collecting the electricity; often called combs. The points
of the combs or collectors face the statically charged rotating glass
plate or cylinder of the machine.
Colombin.
The insulating material between the carbons in a Jablochkoff candle or
other candle of that type. Kaolin was originally used. Later a mixture
of two parts calcium sulphate (plaster of Paris) and one part barium
sulphate (barytes) was substituted.
The colombin was three millimeters (.12 inch) wide, and two millimeters
(.08 inch) thick. (See Candle, Jablochkoff.)
Column, Electric.
An old name for the voltaic pile, made up of a pile of discs of copper
and zinc, with flannel discs, wet with salt solution or dilute acid,
between each pair of plates.