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Adjusting Power Supply Output Voltages Using Fuses

IP.com Disclosure Number: IPCOM000037533D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Simmons, LE: AUTHOR

Abstract

Disclosed is a method to adjust the output voltage of a power supply by using card-mounted fuses.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 99% of the total text.

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Adjusting Power Supply Output Voltages Using Fuses

Disclosed is a method to adjust the output voltage of a power supply by using card-mounted fuses.

When power supply output voltages require tight tolerances, some form of adjustment is needed to meet specifications. The methods commonly used are potentiometers that are adjusted, and parallel resistors that are selectively removed by cutting one lead. Both of these methods require either manual intervention or special fixtures if automated adjustment is required. By using low value fuses in series or parallel with adjustment resistors, most card testers can adjust the power supply output voltage without special fixtures or manual intervention.

If a fuse is placed in series with an adjustment resistor, the resistor can be electrically removed from the circuit by placing a voltage source across the fuse and supplying enough current to open the fuse. If a fuse is placed in parallel with an adjustment resistor, it can be electrically included in the circuit by the same method.

Since a fuse can be placed in parallel or series with an adjustment resistor, this method also allows the pre-tested card to be set at nominal and adjusted from there.

Potentiometers are usually received adjusted to either minimum or maximum value. When cutting resistors, the resistors are in parallel and the combination must be preset to either the circuit minimum or maximum. Both of these methods require more test time for adjustment.

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