Browse Prior Art Database

Diode Fault Detector

IP.com Disclosure Number: IPCOM000088588D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Bellamy, LR: AUTHOR [+2]

Abstract

This article describes a device which utilizes the unique directional and indicating characteristics of an LED (light-emitting diode) for detecting and indicating a defective diode.

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Diode Fault Detector

This article describes a device which utilizes the unique directional and indicating characteristics of an LED (light-emitting diode) for detecting and indicating a defective diode.

Fig. 1 depicts a DC power supply with rectifying diodes D1 and D2 positioned in the output circuit of the secondary winding. In order to detect malfunctioning of diode D2, an LED and series-dropping resistor R are placed in parallel with diode D2. During the half cycle when D2 is conducting, should the diode D2 fail, then the conducting path for the power supply is via R and the LED. Conduction through this path will illuminate the LED and warn an operator that the diode D2 is defective. During the half cycle when D2 is not conducting, the LED cannot conduct due to the unique directional characteristics of the LED and, therefore, the diode will not illuminate.

Fig. 2 depicts an alternate design. In this design a photosensitive transistor T1 is positioned in proximity to the LED. Whenever the LED lights up due to a fault in D2, the transistor outputs a pulse on terminal 10. The signal on terminal 10 is fed to RAS (reliability, availability, serviceability) logic and the power supply is automatically deactivated. Although a transistor is used to receive the light from the LED, any other light-sensitive device may be used to replace T1.

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