GB500736A - Coin freed substation for automatic telephone exchange systems - Google Patents

Abstract

500,736. Automatic exchange systems. TELOFERM SOC. ANON. Aug. 19, 1937, No. 22775. Convention date, Aug. 22, 1936. [Class 40(iv)] - [ALso in Group XVIII] In a coin-freed system of the kind in which the establishment of certain connections is prevented by means of cam-controlled contacts shunting the dial springs, the shunt circuit includes normally closed contacts which can be opened by a privileged person to enable calls to be set up without payment. After passing a gauge E and a magnetic testing apparatus S, N, M³, which ensures its rejection if it is not of nickel, the coin falls on to a pivoted bar W which swings into its position II to shunt the microphone Mi. The dial is arranged to carry round the cam discs Sch1, Sch2 at its first operation and the disc Sch3 at its second operation, and-the discs shown arrange for calls for numbers beginning 12, 14, 15 to be extended free, calls for numbers beginning 2 or 3 to be extended if the appropriate coin is deposited and calls for all other numbers to be prevented. The discs remain in their displaced positions until the end of the call. If a call other than a free call is attempted without inserting a coin, or if a prohibited call is attempted, the impulse springs, K1 are shunted by the latch magnet R over one or more of the contacts K4 .. K7, and a pivoted bar He is allowed to swing clear of contacts K2 to release the exchange apparatus and to remove a plate P from the path of the coin, if such has been inserted, and allow it to enter the refund shoot 4. A successful call is completed by the operation of a cashing-in button D which spills the coin into the box Ka and on release allows the bar W to swing clear of the contacts K3 and so remove the shunt from the microphone. In the case of an unsuccessful call, a link between the switch-hook and the bar He causes the plate P to move to position P11 and allow the coin to enter the refund shoot when the subscriber hangs up. At the same time the discs Sch1 .. Sch3 are restored. The hook switch is of mercury type to make dialling with it impossible. The arm He or the magnet R may control a signal disc. All restrictions may be removed by opening a key-operated contact KS. The switch-hook may control the blocking of and the removal of stuck coins from the coin shoot.