| 摘要 |
PURPOSE:To reset assuredly a circuit when an interlocking key is switched or hooked, by connecting a parallel circuit of the 1st capacitor and a resistance between a reset terminal of a push-button type DP signal transmitting dial control circuit and a power supply terminal at one side. CONSTITUTION:In an off-hook instant, a current flows in a route of a resistance R1 a diode D4 the base of a transistor (TR) Q2 the base of a TR Q1. Then both TRs Q1 and Q2 are turned on, and a trunk loop is closed through a call circuit NW. While an IC completes its resetting when a terminal Vdd exceeds the threshold voltage of the IC and a reset signal received the time control by a reset circuit RS2 is applied to a reset terminal HS. Then a call circuit control terminal M is set at ''H'', and therefore a base current to be supplied to a diode D2 a resistance R5 a resistance R11 and then the base of a TR Q8 is prevented by the OFF of a TR Q3. Thus the TR Q8 is finally kept off; while both TRs Q1 and Q2 are kept at on respectively. |
