| 摘要 |
PROBLEM TO BE SOLVED: To supply a voltage equivalent to a public telephone line from a DC power source generally used on the main body side of a facsimile equipment, etc. to a subscriber's telephone line terminal equipment through the use of a ringing signal generation circuit of a boosting type. SOLUTION: A ringing signal generation circuit 21 is provided with an inductor 21a connected to the DC power source from the main body of the facsimile equipment 1 and a switching transistor 21b switch-controlling a current flowing through the inductor 21a by a high frequency signal to controls an output voltage by the duty ratio of the high frequency signal. Thereby the ringing signal for ringing the subscriber's telephone line terminal equipment 3 cut off from the public telephone line 4 is generated and a voltage equivalent to the inter-line voltage of the public telephone line 4 is supplied for the subscriber's telephone line terminal equipment 3. |
