The Electric Toaster.
—As shown in Fig. 229 the toaster is made of a series of heating elements mounted on mica frames and supported on a porcelain base. It is an example of heating by exposed wires and direct radiation. The heaters H are coils of flat resistance wire that are wound on wedge-shaped pieces of mica. They are supported on a wire frame that is formed to receive slices of bread on each side of the heaters. The attachment piece A and the material of the heater is similar in construction to that of the flat-iron. The electric circuit may be traced from the contacts at A and B in the attachment plug by the dotted lines which indicate the wires in the porcelain base. The current traverses each coil in turn and connects with the next, alternately at the top and bottom. The resistance is such as will permit the voltage of the circuit to send through the coils current sufficient to raise the heaters to a red heat. The added resistance of the hot wires decreases the flow of current to keep the temperature at the desired degree.
Fig. 229.—The electric toaster.
In a heater of this kind the resistance of the wire may increase with age and the coils fail to glow with a sufficient brightness. The reason for the lack of heat is that of decrease in current, due to the increased resistance of the wires. This condition may be corrected by the removal of a little of the heater coils. If a turn or two of the heater wire is removed, the resistance of the circuit is reduced and the effect of the increased current will produce a higher temperature in the heater.