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Analog Multiplication And Division Circuit

IP.com Disclosure Number: IPCOM000097659D
Original Publication Date: 1961-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Dickinson, WE: AUTHOR

Abstract

The light bulb L in the upper circuit is controlled by an amplifier and shines upon a photoresistor R(p1) lowering its resistance. As the intensity of the light increases, the current through R(p1) increases to draw current away from light L so as to reduce its current and hold point x substantially at zero. In this condition, the relationships shown in the equations of lines (1) and (2) are established for a positive analog voltage V(1) used as a divisor.

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Analog Multiplication And Division Circuit

The light bulb L in the upper circuit is controlled by an amplifier and shines upon a photoresistor R(p1) lowering its resistance. As the intensity of the light increases, the current through R(p1) increases to draw current away from light L so as to reduce its current and hold point x substantially at zero. In this condition, the relationships shown in the equations of lines (1) and (2) are established for a positive analog voltage V(1) used as a divisor.

By selecting a photoresistance R(p2) having characteristics substantially identical to those of R(p1), the relationship shown in line (3) is established for the lower portion of the division circuit. Since the two photoresistors are controlled by the same light source and have substantially the same characteristics, the equation in line (2) can be substituted in the equation of line (3). This provides the relationship shown in line (4), namely, that V(0) is equal to a constant k(1) times the ratio of V(2) divided by V(1).

The lower circuit performs multiplication using a similar approach and the relationships of lines (1) and (2) are likewise applicable. The lower portion of the multiplication circuit provides the relationship shown in line (5). If R(p3) substantially matches R(p1) and if R(3) is considerably less than R(p3), substituting the equivalent of R(p3) from line (2) into line (5) establishes the relation in line (6) for the lower half of the multiplying circu...