. American telephone practice . ver off its hook, will cause thelighting of the lamp, L, having a white cap, at the recordingoperators position. The means by which this is brought aboutmay be described as follows: The circuit of the white lamp, L, at therecording operators position is controlled at the back contact oftwo relays, C and D. The relay C is normally de-energized andtherefore keeps its contact in the circuit of the white lamp relay D is, however, normally energized and therefore keepsthe circuit of the white lamp open. The circuit over which the relayD is normally energiz
. American telephone practice . ver off its hook, will cause thelighting of the lamp, L, having a white cap, at the recordingoperators position. The means by which this is brought aboutmay be described as follows: The circuit of the white lamp, L, at therecording operators position is controlled at the back contact oftwo relays, C and D. The relay C is normally de-energized andtherefore keeps its contact in the circuit of the white lamp relay D is, however, normally energized and therefore keepsthe circuit of the white lamp open. The circuit over which the relayD is normally energized may be traced from ground at therecording operators position through the coil of this relay, thencefrom the back contact of the relay B over one side of the trunk lineto the toll-switching operators position at the multiple board, andthence through one winding of the repeating coil through the backcontact of the relay E, to the non-grounded side of the flow of current continues at all times except when the trunk. ^/y^|i|i|i|i|i|4M(WW
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