Method and apparatus for electroanalysis

• US 3,868,578 A
• Filed: 10/02/1972
• Issued: 02/25/1975
• Est. Priority Date: 10/02/1972
• Status: Expired due to Term

• Current Assignee: Trent University
• Original Assignee: Keith B. Oldham
• Inventors: Oldham, Keith B.
• Primary Examiner(s): Zazworsky, John
• Application Number:
  US05/293,780
• Time in Patent Office: 876 Days
• Field of Search: 328/127,128 333/19,20,23
• US Class Current: 327/335
• CPC Class Codes: G06G 7/186 using an operational amplifier comprising a capacitor or a resistor in the feedback loop
• CPC Class Codes: G06G 7/75 for component analysis, e.g. of mixtures, of colours G06G7/122 takes precedence ; gas chromatography G01N30/00

Abstract

An electrical circuit for providing an output signal having a mathematical operation relationship to an input signal, said operation being either that of semi-integration or semidifferentiation, said circuit including an electrical transmission line. The practical circuit for the transmission line comprises a simulated, lumped-constant line made up of a number of series resistance and shunt capacitance elements or series inductance and shunt resistance units. The preferred circuit for effecting semi-integration or semi-differentiation comprises an operational amplifier having a transmission line either in the feedback or in the input. This feedback or input element may take the form of a long (theoretically infinite) transmission line, e.g. a coaxial cable or a lumped constant network of suitably chosen resistance and reactance elements. For electroanalytical measurements the semi-integrating circuit is connected to electrodes positioned in the solution to be measured. Provision is made for applying two predetermined DC voltage levels to the electrodes with the operational amplifier semi-integrating the current flowing between electrodes.

Claims

1. An electrical circuit for providing an output signal having a mathematical operation relationship to an input signal, said operation being semi-integration, comprising a resistance element and an opeRational amplifier in series, the input being applied across the said resistance element and the operational amplifier input, the output being taken across the output of the operational amplifier, the said operational amplifier having a feedback path from output to input connected to the input of a long transmission line section.

2. An electrical circuit as in claim 1 wherein the electrical transmission line is a simulated lumped-constant line made up of a number of series resistanace and shunt capacitance elements of preset values with the ratio of resistance to capacitance in each element being predetermined.

3. An electrical circuit for providing an output signal having a mathematical operation relationship to an input signal, said operation being semi-differentiation, comprising a long transmission line section and an operational amplifier in series, the input being applied across the input to the transmission line and the input to the amplifier and the output taken from the output of the operational amplifier, said operational amplifier having a feedback path from output to input including a resistance element.

4. An electrical circuit as in claim 3 wherein the electrical transmission line is a simulated lumped-constant line made up of a number of series resistance and shunt capacitance elements of preset values with the ratio of resistance to capacitance in each element being predetermined.

5. An electrical circuit for providing a semi-integration operation output according to the following equation V Square Root R/C d 1/2/dt 1/2 i(t) where V is the output voltage of the circuit, i(t), is the input current, the ratio R/C being a predetermined and preset constant, comprising a high gain amplifier having a feedback path connected to the input of a simulated transmission line network made up of a number of series resistance and shunt capacitance elements, the ratio of the summed effective value of the resistance to that of the summed effective value of the capacitances being such as to approximate the ratio R/C of the said equation.

6. An electrical semi-integration circuit as in claim 5 wherein the number of elements is three or more.

7. An electrical circuit for providing a semi-differentiation operation output according to the following equation V Square Root C/R d1/2/dt1/2i(t) where V is the output voltage of the circuit, i(t) is the input current, and the ratio C/R being a predetermined and preset constant, comprising a high gain amplifier having a resistance feedback path and having its input in series with the input of a simulated transmission line network made up of a number of series resistance and shunt capacitance elements, the ratio of the summed effective value of the resistance to that of the summed effective value of the capacitances being such as to approximate the ratio C/R of the said equation.

8. An electrical semi-differentiation circuit as in claim 7 wherein the number of elements is three or more.

9. An electrical circuit for providing an output signal having a mathematical operation relationship to an input signal, said operation being semi-integration, comprising an electrical transmission line and a resistance element with the input to the electrical transmission line connected in series with the said resistance element, the input of the circuit being applied across the series resistance element and transmission line and the output being taken across the input to the transmission line and wherein the electrical transmission line is a simulated lumped-constant line made up of a number of series resistance and shunt capacitance elements of preset values with the ratio of resistance to capacitance in each element being predetermined.

10. An electrical circuit for providing an output signal having a mathematical operation relationship to an input signal, said operation being semi-differentiation comprising an Electrical transmission line and a resistance element with the input to the electrical transmission line connected in series with the said resistance element, the input of the circuit being applied across the series resistance element and transmission line and the output being taken across the resistance element and wherein the electrical transmission line is simulated lumped-constant line made up of a number of series resistance and shunt capacitance elements of present values with the ratio of resistance to capacitance in each element being predetermined.