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Microamps current multiplier

IP.com Disclosure Number: IPCOM000013138D
Original Publication Date: 2003-Jun-16
Included in the Prior Art Database: 2003-Jun-16
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Abstract

Multiplying a micro amp level current by any ratio.

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Microamps current multiplier

Application of the invention:

Any electronic system needing to multiply a small current, for example, when a current of ten micro amps must be measured on a full scale and only a one hundred micro amp galvanometer (the most familiar) is available.

Description of the invention :

By reference to the figure, the current I in the Rx resistor must be measured. Since the impedance is very high on the pin minus of the operational amplifier, this current crosses the R resistor. When connecting another resistor, nine time smaller (R/9), the resulting current in this resistor is nine time bigger. Since the sum of all the currents is equal to zero at the point referred to as P, the current in the galvanometer is ten times bigger than I.

It provides a current multiplier by ten and, as one can observe, only the resistor ratio is important in the multiplying scale factor.

R/9

OP am p

R 9 x I

10 x I

I

Rx I

P

-

+

A

v

FIGURE 1

Disclosed by International Business Machines Corporation

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