| 摘要 |
1,090,196. Transistor switching circuits. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. May 11, 1966 [May 12, 1965], No. 20894/66. Heading H3T. A temperature-compensated circuit, responsive to a control voltage exceeding a threshold value, and having a high input resistance, comprises two reciprocally coupled transistors T1, T2, the control voltage being applied to the base of transistor T1 through a Zener diode D3 connected in reverse with respect to the control voltage and providing the temperature compensation. In the embodiment shown, an A.C. input is rectified and doubled by circuit D1, D2, C1, C2, and when it exceeds a first threshold value, Zener diode D3 is caused to conduct and the state of bi-stable circuit T1, T2 is changed to transistor T1 conductive; T2 blocked. At the same time, diode D4 becomes non-conductive and diode D5 becomes conductive. The circuit reverts to its original state when the input falls below a second, lower threshold. Diodes D4, D5 and resistor R6 may be omitted (Fig. 2, not shown), but their inclusion results in an increased operating hysteresis. |
