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US 4,053,832 AGranted
A.C. power meter
AssigneeNational Semiconductor Corporation
InventorCarl T. Nelson
Life of this patent
Estimating the term…
Abstract
A pair of PNP and a pair of NPN transistors are connected in a balanced self clamping circuit in which the output response is proportional to the product of transistor emitter current and differential base voltage. The circuit is linear and accurate for use in reading true (in-phase) power in an a-c circuit.
Claims6
A multiplier circuit comprising:
- First and second PNP transistors and first and second NPN transistors, each of said trainsistors having emitter, base, and collector electrodes,
- means coupling the emitters of all of said transistors to a first terminal,
- means coupling the collectors of said first NPN and said second PNP transistors together,
- means coupling said coupled first NPN and second PNP collectors to a second terminal,
- means coupling the collectors of said second NPN and said first PNP transistors together,
- means coupling said coupled second NPN and first PNP collectors to said second terminal,
- means coupling the bases of said second PNP and NPN transistors together and to said second terminal,
- means coupling the bases of said first NPN and PNP transistors together and to a third terminal, and
- means for sensing the difference in value between the combined currents of said first NPN and said second PNP transistors and the combined currents of said second NPN and said first PNP transistors whereby said means for sensing responds to the product of the current flowing in combined transistor emitters and the voltage difference existing between the coupled bases of said first NPN and PNP transistors and the coupled bases of said second NPN and PNP transistors.
6 more elements
Dependencies are inferred from the claim text.