Browse Prior Art Database

Capacitor Tester

IP.com Disclosure Number: IPCOM000049306D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Olsen, FW: AUTHOR

Abstract

Automatic range selection is combined with differential testing of the changing rates of capacitors to provide an efficient, accurate indication of capacitor performance.

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Capacitor Tester

Automatic range selection is combined with differential testing of the changing rates of capacitors to provide an efficient, accurate indication of capacitor performance.

In the figure, capacitor 1 under test is charged by current source 2 when shorting switch 3 is opened. The ramp voltage on line 4 is applied simultaneously to the inputs of three differentiating range selection circuits 5a, 5b and 5c. The component arrangement of each of these circuits is the same except for the differences noted for amplifiers 7a, 7b and 7c.

Referring to differentiation circuit 5a, the input ramp to the capacitor is expanded at amplifier 6 and differentiated in a counteracting fractional scale differentiator 7a to restore the true value and provide an input to a second differentiator 8 and to sample and hold circuit 9. The second differentiation determines the slope of the ramp signal. When the slope is zero, and output from window comparator 10 appears at gate 11. This gate is controlled by a slightly delayed signal from delay 12, indicating the opening of shorting switch 3.

When gate 11 is enabled, its output sets latch 13 whose output in turn commands sample and hold circuit 9 to sample the output of differentiator 7a. The output of sample and hold circuit 9 is supplied to the normally open (N/O) terminal of analog switch 14.

Differentiator circuits 5b and 5c operate in the same manner except that their respective scales are one tenth and one hundredth that...