| 摘要 |
PURPOSE:To eliminate the shortage of electric power for drive of a loop formation relay by using the 1st power supply circuit which performs the trickle charge to supply the power only to a system necessary for drive of said relay. CONSTITUTION:In an on-hook mode only power supply capacitors C10 and C11 are trickle-charged by a constant voltage diode ZD1 and power supply voltage VA and TLP are supplied to an A block circuit 1000 and a loop formation relay LP. Here a hook switch HS2 is closed when a calling subscriber hooks off a handset. Thus an oscillation circuit 700 is actuated. Then a photocoupler CC3 is cut off when coins are supplied, and the output of an AND circuit 9 is set at L with an FF1 set. Then the relay LP is driven. The charging is started to capacitors C12-C14 from the diode ZD1 with actuation of the LP. Thus the voltages VB, TLS and CM are supplied to a B block circuit 2000, a store magnet LM, etc. |
