Patent GB-1196549-A (GB)
Title: Improvements in or relating to methods of Converting Pulsetrains
IPC: H04M17/02
Filed: 1968-09-27
Abstract: 1,196,549. Electronic counters. SIEMENS A.G. 27 Sept., 1968 [29 Sept., 1967], No. 45882/68. Heading G4A. [Also in Divisions H3 and H4] Metering pulses arriving at a prepayment substation are entered into a first store from where they are transferred in step-by-step manner to a second store which thereby periodically produces coin pulses, the number of steps required for reading out each metering pulse being determined by the relative values of the metering and coin pulses. In the German system described each metering pulse corresponds to a charge unit of 18 pfennig and each coin pulse to a value of 10 pfennig which is the minimum value coin acceptable by the coin box. If the same metering pulse rate is to be used for all types of subscribers it is therefore necessary to convert each metering pulse into a fractional multiple of 10 pfennig at the prepayment stations so that such stations-after an initial fee-may be charged in multiples of 10 pfennig. It is mentioned that a method of selectively charging a capacitor by metering pulses and then discharging it against the discharge of a reference capacitor is known for producing coin pulses at the requisite relative rate but that numerous inaccuracies arise with this method. In the present embodiment each arriving metering pulse operates a relay J (not shown) which causes a multistable core K1 to be saturated in the negative direction by momentary change-over of contacts i 1 , i 2 - When the pulse ceases, a self-stepping relay A (or a pulse generator) is actuated so as to periodically reverse the saturation of a core K3. Each such reversal causes the magnetization of core K1 to be stepped by one increment towards positive saturation while at the same time the magnetization of a core K2 is stepped by one different increment towards negative saturation. By suitable choice of the winding ratios of W2 and W3, it is ensured that the core K1 requires 18 steps to reach positive saturation whereas the core K2 only requires 10 steps to reach negative saturation. Upon attainment of tne latter, the sudden increase of current through resistor R2 is effective via a transistor amplifier to bring up relay C which temporarily stops A and produces a coin pulse. When C relapses, A restarts and the stepping of the two cores K1, K2 recommences. When K1 becomes saturated, the increase of current through R1 is effective to bring up relay B in order to stop A until a further metering pulse arrives. At this point core K2 "contains" 8 magnetization steps and thus only two more steps thereof will be necessary upon reception of the next metering pulse before another coin pulse is transmitted. In order to ensure that the core K1 is restored to the initial positive saturation state before the arrival of a next metering pulse, it is mentioned that the interval between the first two metering pulses (initial fee) received during a call are used to adjust the stepping rate of the pulse generator (relay A) although no details of this adjustment are given. It is further suggested that the cover K1, K2 may be replaced by ring counters which are caused to step in a similar manner under the control of a pulse generator. The relay contacts a 3 , a 4  may be replaced by transistor switches which are controlled by additional windings on core K3.