Ringer Capacitor
The 1.9-mf capacitor in Telephone EE-8, or the 2.0-mf capacitor in Telephones EE-8-A and EE-8-B, is in series with the ringer when the screw switch is in the CB position. This capacitor prevents direct current from biasing the ringer and also pre­ vents the ringer from interfering with d-c signaling or supervision when the telephone is connected to a common battery system. The capacitor is short-circuited when the screw switch is turned to the LB position.
The transmission loss through the ringer, or the ringer and the capacitor in series, and the holding coil is negligible because of the high impedance to voice-frequency currents of these elements.