| 摘要 |
PURPOSE:To obtain a voltage detecting circuit having the same ratio between the active and reset voltage levels against two rated voltage levels, by connecting a control resistance between both output terminals of a Schmitt circuit and a constant voltage circuit and turning on and off the current flowing to the control resistance to produce a difference of voltage drop produced by an input resistance between the active and reset modes. CONSTITUTION:The current I0 flowing to an input resistance 18 is approximately equal to the output current of an AC bridge rectifying circuit 1 and also equal to the totals sum of the currents I1-I4 flowing to voltage dividing resistances 5 and 6, a Zener diode 10, voltage dividing resistances 13 and 14, and an output circuit 20 respectively and a current I5 flowing to a control resistance 19 respectively. Here the current I1 increases in proportion to the voltage V4 and other currents I2-I5 flow only when a constant voltage circuit 2 reaches its normal working level. Furthermore the levels of those currents are kept at comparatively low values excepting for the current I5. While the current I5 is comparatively increased and decreased when the output signal S of a Schmitt circuit 3 is set at a low level and a high level respectively. Here the relation between both voltages Vn1 and V4 is shown by a straight line A in the figure in case the voltage is applied to the 100V-rated voltage terminals 4a and 4b.
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