| 摘要 |
A dynamic discharge circuit for a capacitively-charged electrical device includes, in one embodiment, a bipolar transistor placed in the discharge path, with the base of the transistor being connected so that conduction is held off by the voltage generated by an illuminated PV-diode. When the PV-diode is shut off, base-drive is immediately supplied through a base resistor in dynamic fashion by the very capacitive charge that is to be discharged. In another embodiment, the resistor is replaced with a diode-transistor combination, thus eliminating the delaying RC product inherent with the use of a resistor. In yet a further embodiment, an SCR placed in the discharge path is also dynamically driven. Discharge times on the order of about 5 microseconds are attained with the latter two embodiments and it is found that this discharge time is relatively constant regardless of the value of the capacitance to be discharged. The embodiments are described as being applied to the discharge of a capacitively-charged MOSFET in an optically-coupled solid state relay.
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