Patent EA-001124-B1 (EA)
Title: Device for indicating changes in the resistance of a living body, a feedback and control circuit for use in a device, method for maintaining a generally constant amplitude response
Inventor: MCCORMICK JOHN
IPC: H04H1/00
Filed: 1997-03-24
Abstract: 1. A device for indicating changes in the resistance of a living body comprising: a resistance measuring circuit having external leads; an amplifier circuit connected to the resistance measuring circuit; an indicator circuit connected to said amplifier circuit; and a sensitivity adjustment circuit connected to said amplifier circuit, wherein said resistance measuring circuit is adapted to measure resistances within a first range of relatively low variable resistances, to measure resistances within a second range of relatively high variable resistances across a living body and to produce a measured signal, an amplifier circuit is adapted to amplify the measured signal to a perceptible level; an indicator circuit is adapted to produce the measured signal in a perceptible form; and  a sensitivity adjustment circuit means is adapted for automatically increasing sensitivity of said indicator circuit in setting for a high variable resistance in said second range measured in said resistance measuring circuit, said sensitivity adjustment circuit means is adapted for automatically adjusting sensitivity of said indicator circuit for a low variable resistance in said second range measured in said resistance measuring circuit. 2. The device for indicating changes in the resistance of a living body of claim 1 wherein said means for automatically increasing sensitivity includes a control circuit. 3. The device for indicating changes in the resistance of a living body of claim 1 wherein said means for automatically increasing sensitivity includes a control circuit. 4. The device for indicating changes in the resistance of a living body of claim 1 wherein said means for automatically increasing sensitivity includes a voltage controlled operational amplifier. 5. The device for indicating changes in the resistance of a living body of claim 1 wherein said amplifier circuit including a calibration circuit operative to automatically adjust the gain of said amplifier circuit in response to movement of said adjustment potentiometer. 6. The device for indicating changes in the resistance of a living body of claim 5 wherein said calibration circuit includes: a feedback circuit responsively connected to said resistance measuring circuit to receive a signal representative of a measured input; a control circuit responsively connected to said feedback circuit to determine a compensation value using said measured input signal; and a compensator circuit responsive to said control circuit to adjust said amplifier circuit gain by said compensation value to maintain a generally constant amplitude response. 7. The device for measuring and indicating changes in the resistance of living body of claim 6 wherein said calibration circuit includes a feedback circuit adapted to receive signals representative of the overall resistance of a living body. 8. The device for measuring and indicating changes in the resistance of living a body of claim 7 further including control circuit connected to said feedback circuit and adopted to determine from said input signal a compensation signal corresponding to a change in the gain of the amplifier circuit. 9. The device for measuring and indicating changes in the resistance of living body of claim 7, wherein said calibration circuit includes a compensator circuit adapted to receive said compensation signal and to adjust said amplifier circuit to maintain a generally constant amplitude response. 10. A feedback and control circuit for use in a device for indicating changes in the resistance of a living body, said feedback and control circuit comprising: a feedback circuit operatively connected to said device to monitor a known condition; a control circuit responsively connected to said feedback circuit to receive signals representative of said known condition and to infer from said signals an appropriate corrective response; a compensator circuit responsively connected to said control circuit to adjust for said known condition. 11. The feedback and control circuit of claim 10, wherein including a software program executed by said control circuit, said program including: means for reading signals of said known condition from said feedback circuit; means for anticipating and determining a response to an undesirable characteristic using signals representative of said known condition; means for generating a response to said undesirable characteristic; and means for adjusting said compensator circuit to eliminate said undesirable characteristic. 12. The feedback and control circuit of claim 11 wherein said anticipating and determining means includes a sleep mode. 13. The feedback and control circuit of claim 11 wherein said anticipating and determining means includes sensing stability in said known condition. 14. The feedback and control circuit of claim 11 wherein said control circuit includes an analog to digital convertor and said anticipating and determining means includes reading data generated from said analog to digital convertor. 15. A device for indicating changes in the resistance of a living body comprising: a resistance measuring circuit having external leads;  an amplifier circuit having external leads;  an indicator circuit having external leads;  a plurality of manually controlled devices, having leads extending therefrom; and wherein at least one lead extending from each of said circuits and from each of said manually controlled devices and at least one inductor included within said resistance measuring circuit and within said amplifier circuit whereby radio interference conducted through said circuits is reduced. 16. A device for indicating changes in the resistance of a living body comprising: a resistance measuring circuit; an amplifier circuit; an indicator circuit; and wherein includes a housing surrounding said resistance measuring circuit, said amplifier circuit and said indicator circuit; and  a radio frequency insulating paint coating said housing. 17. A method for maintaining a generally constant amplitude response to a predetermined measured input in a device for measuring changes in the resistance of a living body, the device having a resistance measuring circuit, comprising: initializing said resistance measuring circuit and said amplifier circuit; connecting a living body to said resistance measuring circuit; establishing the overall resistance in the living body; and adjusting the gain of said amplifier circuit according to a predetermined ratio such that a generally constant amplitude response is generated for a measured change in resistance via a computer interface. 18. The device of claim 5 wherein said amplifier circuit includes an op-amp having a capacitor connected in circuit between positive and negative inputs to said op-amp. 19. The device of claim 6 wherein said control circuit further includes a microcontroller connected to said feedback circuit. 20. The device of claim 6 wherein said control circuit further includes:  an activation circuit adapted to activate said control circuit upon transition of said manual adjustment potentiometer. 21. The device of claim 6 further including  a microcontroller in said control circuit and which is connected to said feedback circuit and  computer-implemented software operatively controlling said microcontroller and including a calibration input signal compensator circuit. 22. The device of claim 21 further including a calibration input signal compensator circuit and a digital potentiometer connected to said amplifier circuit. 23. The device of claim 5 further including: a microcontroller in said calibration circuit; computer-implemented software adapted to configure said calibration circuit, to continuously detect changes in the manual adjustment potentiometer, and to determine and set a resolution mode from a set of predetermined resolution modes. 24. The method of claim 17 further including: manually adjusting a potentiometer as part of establishing the overall resistance; and  setting a resolution mode for establishing overall resistance of the living body to one of a plurality of predetermined resolution modes. 25. The method of claim 24 further adjusting the gain of said amplifier circuit by matching predetermined compensation factor signals to predetermined resistance change values corresponding to changes in the overall resistance in the living body.