| 摘要 |
PURPOSE:To obtain a small-sized ringer power supply suitable for a subscriber terminal, by boosting a high-frequency power supply and switching this rectified voltage at a ringer frequency. CONSTITUTION:A comparator 5 is blocking-oscillated at a frequency determined with a comparison voltage at a noninverting terminal 6, a capacitor C1 and a resistor R1. Comparators 15, 16 are similarly blocking oscillators, and the comparator 15 is used for the ringer frequency and the comparator 16 interrupts the ringer frequency at a prescribed frequency. The output of the comparator 15 controls a switching circuit 14 to shape the ringer frequency. Thus, the more the frequency is increased, the better power transmission rate of a transformer has, thus the ringer power supply circuit can be made small in size by using a suitable high-frequency power transformer 9. |
