GB343770A - Improvements in or relating to telephone pay stations - Google Patents

Abstract

343,770. Automatic exchange systems. TELEPHON-APPARAT - FABRIK E. ZWIETUSCH & CO., GES., 6, Salzufer, Charlottenburg, Berlin. March 8, 1930, No. 7675. Convention date, May 17, 1929. [Class 40 (iv).] In order to avoid dishonest recovery of a coin after an effective call in telephone prepayment stations arranged for coin collection at the end of conversation by a collecting magnet, a relay provided at the exchange is adapted to store the collecting impulse, viz. the metering impulse, and render the circuit unfit for conversation until the collecting magnet is operated. As shown, a device V driven by clockwork, which is wound by operation of the switchhook HU, closes a contact in the circuit of the collecting magnet KM for a predetermined time upon restoration of the receiver upon the switch-hook and then actuates the coin restoring mechanism. When after a successful call, the receiver is replaced slow-release relay Z at the exchange pulls up over winding ZI and locks over winding ZII in series with resistance Wi. The circuit of relay ZH is prepared over contact z2 and when the device V connects the collecting magnet KM to line b relay ZH is energized in series with magnet KM. Relay ZH short-circuits winding ZII, and thereby releases relay Z but relays KM, ZH remain operated over zh1 until the device V switches the collecting magnet from the line and restores the speaking circuit. Any attempt to recover a coin by fraudulent means, e.g. operation of the impulse springs to cause release of the connection, is prevented since relay Z is operated in such circumstances to store the collecting impulse and ensure operation of the collecting magnet KM when the switch-hook is actuated. For ineffective calls, relay Z and magnet KM remain inoperative and the coin restoring mechanism is subsequently operated. Contacts MK are operated upon insertion of a coin to open short-circuit across the impulse contacts JK.