| 摘要 |
PURPOSE:To prevent the mis-reception of inserted coins due to the collision of incoming and outgoing calls, with a simple constitution, by providing the reversing close relay operated through the detection of the first dial signal after a coin is inserted and by inserting the contacts of the relay in the reversing loop. CONSTITUTION:In the public telephone set of push button dial system which closes the DC loop between the station and the set with the insertion of a coin, the push button dial oscillation circuit OSC of the telephone set T is connected to the diode bridge and the current detection section C is connected between the diode junctions of D1 and D2 constituting the telephone set T and the diode bridge. This detection section C detects the presence of the push button operation, the detected output is connected to the control section CU, and the coin storage contact CC and the output of the hook switch HS3 controls the reversing loop closing relay RL. The normally open contact rL of this relay RL is connected in series with the diode D4, the first dial oscillation signal after the coin is inserted is detected, to form the reversing loop. |
