Testing apparatus for electrical device where a stimulus is varied between two states

Claim 2

Testing apparatus for testing an electrical device having at least one input and an output said apparatus comprising a first high gain amplifier having an input coupled to said output of said device and an output, first negative feedback means for coupling said output of said first amplifier to said input of said device, a second high gain amplifier having an input and an output, second negative feedback means for coupling said output of said second amplifier to said input of said device, means for varying a stimulus to said device between two states, and switching means having open and closed conditions for coupling said output of said first amplifier to said input of said second amplifier during the first one of said states of said stimulus and decoupling said second amplifier from said first amplifier during the second of said states.

Claim 3

Testing apparatus as in claim 1 in which said second amplifier includes means for holding its output when its input is disconnected by said switch opening.

Claim 4

Testing apparatus as in claim 1 together with display means coupled to the output of said first amplifier when said second amplifier is decoupled, the magnitude of the signal on such output being proportional to the test data desired.

Claim 5

Testing apparatus as in claim 1 in which said device has two inputs and the stimulus being varied is the common mode voltage being applied to said two inputs, said voltage in one state being a positive value and in another state a negative value said output of said first amplifier being proportional to the common mode rejection characteristic of said device when said second amplifier is decoupled.

Claim 6

Testing apparatus as in claim 1 in which said first and second feedback means varies the magnitude of output signal of said device to maintain a substantially zero input voltage to said first amplifier during both states of said stimulus.

Claim 7

Testing apparatus as in claim 1 together with variable voltage supply means coupled to said output of said device and in which the stimulus being varied is the signal magnitude of said variable voltage supply means, such voltage supply means coupling a voltage of one polarity to said device output when said switch closed and a voltage of an opposite polarity when said switch is open, the signal magnitude of the output of said device being adjusted by said first and second feedback means to provide a substantially zero input voltage to said first amplifier during both states of said stimulus.

Claim 8

Testing apparatus for testing an electrical device comprising: sequencer means for subjecting said device to a plurality of sequential tests by sequentially varying a stimulus to said device between a first state and a second later state for each of said tests; a plurality of manually operable switch elements each corresponding to one of said tests; logic means coupling said switch elements to said sequencer means and responsive to actuation of any one of said switch elements for initiating operation of said sequencer means to sequentially vary said stimulus and sequence through said plurality of tests; means coupled to said device for providing a digitized test result voltage which is generated in response to said stimulus being placed in said second state; counter means for receiving said digitized test voltage; means coupled to said counter means for comparing its contents with a reference standard at a predetermined time and providing a qualitative, pass-fail, visual indication of said test results; means for quantitatively displaying the contents of said counter means; and logic means coupled to said switch elements for coupling said quantitative display means to said counter means and for transferring the contents of said counter means to such display only for a test associated with one of said switch elements which has been actuated such actuation enabling said transfer function of said logic means.

Claim 9

Testing apparatus for testing an electrical device comprising: sequencer means for subjecting said device to a plurality of sequential tests by sequentially varying a stimulus to said device between a first state and a second later state for each of said tests; a plurality of manually operable switch elements each corresponding to one of said tests; logic means coupling said switch elements to said sequencer means and responsive to actuation of any one of said switch elements for initiating operation of said sequencer means to sequentially vary said stimulus and sequence through said plurality of tests; means coupled to said device for providing a digitized test result voltage which is generated in response to said stimulus being placed in said second state; counter means for receiving said digitized test voltage; means coupled to said counter means for comparing its contents with a reference standard at a predetermined time and providing a qualitative, pass-fail, visual indication of said test results; means for quantitatively displaying the contents of said counter means; and logic means coupled to said switch elements for coupling said quantitative display means to said counter means and for transferring the contents of said counter means to such display only for a test associated with one of said switch elements which has been actuated such actuation enabling said transfer function of said logic means.

Claim 10

Apparatus as in claim 7 together with an additional manually operable switching element coupled only to said sequencer means for initiating operation of said sequencer means.

Claim 11

Apparatus as in claim 7 where said pass-fail indication means is responsive to the most significant bit of the contents of said counter means to provide such indication.

Claim 12

Apparatus as in claim 7 where said means for providing a digitized test result voltage includes a variable gain amplifier for normalizing said test results to a single standard.

Claim 13

Apparatus as in claim 10 where said means for providing a digitized test result voltage also includes a removable printed circuit program board having resistors thereon which establish stimulus level and gain levels for said variable gain amplifier.

Claim 14

Apparatus as in claim 11 where said board also includes a socket for the device being tested.

Claim 15

Apparatus as in claim 11 where said board includes printed circuit drill-outs for inhibiting said pass-fail indication.