RESISTANCE MEASUREMENT SYSTEM

• US 3,772,593 A
• Filed: 11/03/1971
• Issued: 11/13/1973
• Est. Priority Date: 11/03/1971
• Status: Expired due to Term

• Current Assignee: Pawitter S. Sidhu
• Original Assignee: Pawitter S. Sidhu
• Inventors: Sidhu, Pawitter S.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/195,331
• Time in Patent Office: 741 Days
• Field of Search: 324/62R,71R 128/2.1Z
• US Class Current: 324/692
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00

Abstract

A resistance measurement system for measuring the change in the value of a resistance. An input circuit provides an output signal proportional to the value of the resistance. The output of the input circuit is coupled to an amplifier circuit which provides an amplified output signal representative of changes in the resistance. The output of the amplifier circuit is coupled to a display circuit which provides an indication when the resistance has increased or decreased a predetermined amount. Alternatively, the input circuit may provide an indication of the percentage change in the value of the resistance.

Claims

1. A resistance measuring system for measuring the varying change in the value of resistance comprising:

a. input circuit means for providing a first output signal proportional to the value of said resistance as said resistance varies;

b. an amplifier circuit having said output signal coupled to the input thereof;

c. whereby said amplifier circuit produces an amplified output signal proportional to the variation in said resistance and d. indicator means connected to said amplifier circuit for producing an indication representative of both the increase and decrease in said resistance.

2. A resistance measuring system in accordance with claim 1, wherein said first output signal is an indication of the percentage change in said resistance.

3. A resistance measuring system in accordance with claim 1, wherein said amplifier circuit includes filtering means for decoupling the input DC level from the amplifier input, said amplifier circuit thereby amplifying only changes in said resistance.

4. A resistance measuring system in accordance with claim 1, wherein said indicator means provides a first output indication when said resistance increasEs beyond a predetermined level and a second output indication when said resistance decreases below said predetermined level.

5. A resistance measurement system in accordance with claim 1, wherein said input circuit is responsive only to changes in said resistance.

6. A resistance measuring system in accordance with claim 1, wherein the AC current of said input circuit is proportional to ( Delta R/R) where Delta R is the incremental change in said resistance;

and R is the value of said resistance.

7. A resistance measuring measuring for mesuring the change in the value of a resistance comprising:

input circuit means for providing first output signal proportional the value of said resistance;

an amplifier circuit having said output signal coupled to the input thereof, said amplifier circuit producing a second output signal proportional to the change in said resistance;

indicator means connected to said amplifier circuit for producing a third output representative of a change in said resistance, wherein said input circuit comprises a transistor connected in emitter-follower configuration, said resistance being coupled across the base-collector circuit of said transistor and wherein amplified output signals representative of said value of resistor are coupled from the emitter of said transistor to a filter the output signal of which is representative of changes in said resistance, and wherein said filter output signal is coupled to an operational amplifier, and further wherein said output operational amplifier is coupled to a pair of transistors, one of said transistors being conductive when said resistance change increases beyond a predetermined value and the other of said transistors being conductive when said resistance change decreases beyond a predetermined value.

8. A resistance measuring system in accordance with claim 1 including a pair of electrodes connected to said input circuit adapted to contact the resistance to be measured.