In construction, the loose coupler consists of a primary winding much the same as an ordinary tuning coil provided with a single slider.
A second winding called the secondary, divided into a number of sections and adjustable by means of a multi-pointed switch mounted on one end, slides in and out of the primary.
LESSON TWENTY-FIVE. FIXED CONDENSERS.
A fixed condenser usually implies the condenser used in the receiving circuit to furnish part of the necessary capacity and to shunt the telephone receivers, or as in cases where a battery is used in connection with the detector to force the current to choose a path through the comparatively low resistance turns of the tuning coil.
FIG. 54. Fixed Condenser.
A fixed condenser, as its name implies, has a fixed value or capacity. It is usually constructed of sheets of tinfoil interposed between sheets of thin paraffined paper or mica. The capacity of a fixed condenser usually varies from .002 to .005 microfarads.
An alternating current passes readily through a condenser but a direct current is effectually blocked.
When a direct current is led into a condenser as shown in the diagram, the half of the condenser represented by A becomes positively charged. When A receives a positive charge it repels the positive charge from B and attracts the negative thus making B negative. There is no change in the direction of the current after the first connection and the charge remains fixed and no currents pass.
