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One Exclusive or for Two Different Tests on Printed Circuit Lines

IP.com Disclosure Number: IPCOM000081968D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Fitzpatrick, GE: AUTHOR [+2]

Abstract

Multiple printed-circuit lines of approximately equal spacing, size and length are respectively tested for continuity and electrical isolation.

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One Exclusive or for Two Different Tests on Printed Circuit Lines

Multiple printed-circuit lines of approximately equal spacing, size and length are respectively tested for continuity and electrical isolation.

The two tests are accomplished by the use of a single exclusive OR (XOR) circuit and difference amplifier per circuit line. Only one input to the exclusive OR is varied.

The output of the XOR (Fig. 2) is applied to the base of a transistor T1. The emitter of the transistor has a variable resistor R2 to ground. With R2 = R1, the output at D may be varied from approximately v/2 to ground.

In Fig. 2, Test 1 - Input A is negative, in the absence of a positive clock pulse applied to input B, output D is positive. The positive clock pulse causes output D to go negative for the duration thereof. (Fig. 3).

In Fig. 2, Test 2 - Input A is positive, in the absence of a positive clock pulse applied to input B, output D is negative. Output D is positive for the duration of the positive clock pulse (Fig. 3). As explained hereinafter, this allows two tests to be accomplished by varying only input A.

Two or more adjacent printed-circuit lines are tested as follows: Test 1 is employed to determine if the lines are respectively not open; and Test 2 is employed to determine that there are no shorts between lines. These two tests may be employed to test printed-circuit lines, cables, etc.

Typical test procedure: Reference is made to Fig. 1, assume the following test

conditions:

Test 1: Each line is not open, and has a resistance of less

than 30 ----- . (continuity test).

Test 2: Each line is not shorted to any other line. A

short being defined as anything less than 100K ---- .

(isolation test).

TEST 1: (1) Initially all A inputs are negative and B

inputs are

negative causing points C to be negative. The X end...