| 摘要 |
1,237,002. Semi-conductor monostable circircuits. INTERNATIONAL STANDARD ELECTRIC CORP. 11 Sept., 1968 [14 Sept., 1967], No. 43144/68. Heading H3T. The duration of the unstable period of a monostable circuit is controlled by the switchoff delay in at least one three-electrode semiconductor element. A trigger pulse applied at 12 or 13 to a bi-stable circuit 1, 2 switches the circuit to a state in which transistor 2 is off. Transistor 3 switches on and after a time delay while charge carriers stored in the base leak away, transistor 4 switches off. The resulting output pulse from 4 restores the bi-stable circuit to its initial state. A potentiometer 20 and a further resistor which may be connected to the base of 3, adjusts the rate of leakage of the base charge. The coupling resistors 14 and 15 can be replaced by diodes or emitter followers which provide a large forward base current but present a high resistance to the reverse base current. In Fig. 4, not shown, transistor 4 is omitted and the delayed feedback is provided from 3 to the base of 1, transistors 2 and 3 effecting the delay. |
