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Detection of Shorted Components in Parallel Circuits

IP.com Disclosure Number: IPCOM000082747D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Becker, JD: AUTHOR

Abstract

A system utilizing an alternating drive current and a synchronous detection amplifier allows practical measurement of voltages as low as a microvolt or less. This sensitivity makes possible the practical measurement of voltage drops in component leads and, thus, the detection of shorted components.

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Detection of Shorted Components in Parallel Circuits

A system utilizing an alternating drive current and a synchronous detection amplifier allows practical measurement of voltages as low as a microvolt or less. This sensitivity makes possible the practical measurement of voltage drops in component leads and, thus, the detection of shorted components.

Components 1 and 2 are mounted in parallel in the circuit connected between nodes 3 and 4. Resistors R1-R4 represent the resistance of the conducting leads of components 1 and 2 and/or the resistance of the printed-circuit board foil conductors used in wiring the parallel circuit. If either of components 1 or 2 become shorted or exhibit a relatively low-leakage resistance, current will flow between nodes 3 and 4 if a voltage is impressed across these nodes.

To determine which of the components 1 or 2 is exhibiting the lower resistance, the voltage drops across R1 and R3 are measured and compared or, alternatively, the voltage drops across R2 and R4 are measured and compared. The component 1 or 2 in series with the resistor exhibiting the greater voltage drop is then determined to be the shorted or leaky component.

Square-wave oscillator 9 drives power amplifier 10 to produce an amplified square-wave output voltage that is applied to node 3. Input lead 11 of differential AC amplifier 13 is connected to node 3, while input lead 12 of amplifier 13 is alternately connected between nodes 14 and 15. The output of amplifier...