| 摘要 |
PURPOSE:To realize the integration with a miniature size for the control circuit which stores the telephone call charge after talking by charging previously the capacitor via the main wire source given from the exchange and then discharging the charged electric charge to drive temporarily the holding magnet. CONSTITUTION:In case the call charge is stored for the public telephone with use of the main wire source given from the exchange connected to line terminal L1 and L2, capacitor C3 and C4 are charged and driven when holding magnet RM is turned on by hook switch HS1 in order to inhibit the return of the stored coins. At the same time, the output of pulse generator PG which is actuated by charge voltage V of capacitor C4 provided at control circuit CT and then generates the fixed pulse duration T is applied to transistor Tr2 forming the charging circuit, and capacitor C3 is charged only for the time of pulse duration T. And when the talking is over with hook switch HS2 turned off, the output of generator PG is applied to Tr1 forming the discharging circuit. Thus, the operation of magnet RM is stopped to return the stored coins. |
