| 摘要 |
1,182,066. Transistor switching circuits. SOC. ITALIANA TELECOMUNICAZIONI SIEMENS S.p.A. 4 July, 1968 [6 July, 1967], No. 31892/68. Heading H3T. An electronic sampling switch for time-division multiplex telecommunication systems in which a capacitor can be switched to either a charging voltage or across a transistor switch which is operated by the discharge current. In Fig. 2, the sampling switch of coupled transistors TR1, TR2 is closed when a sampling pulse at P causes A3 to saturate giving charged capacitor C a discharge path via TR1, TR2. At the end of the pulse, A3 is cut off, transistor A2 saturates and diode A1 is forward biased. C is now charged via diode D and resistor R<SP>1</SP>, the voltage across the latter blocking TR1, TR2. D and R<SP>1</SP> form a low-resistance path for the charge current such that the blocking of TR1, TR2 and the charging of C occur soon after the disappearance of the pulse at P; similarly, spurious currents flowing whilst TR1, TR2 are blocked cause a voltage across R<SP>1</SP> which enhances the blocked condition. |
