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Lighted power cable

Function

Some power supplies, often from Fruit, have those pretty connectors with built-in LEDs that shine when there is power present.

It was decided that the workshop wall-warts needed such upgrade, for increased awareness of what connectors are powered, and when the switching power supply is not able to provide enough power and is shutting itself down. (Also for voltage sags.)

Method

A simple circuit with a green LED and a 2.2 kΩ resistor was used as the indicator. A fairly high resistor value was chosen so the light would be just bright enough to be easily visible without being visually overpowering in a dimly lit workshop.

A power supply cable with a barrel jack connector was taken, cut lengthwise, pieces of insulation were removed on not-exactly-opposite ends (to avoid short circuit by direct contact). A small leaded resistor (as small as can be sourced) of 2.2 kiloohm value was soldered in series to a 3mm green LED, its dome ground from sides to a tip so it would better fit into the fork of the wire. The diode-resistor assembly then was placed between the wires and soldered to the uninsulated spots on the cable.

The whole assembly was then potted in translucent hot-melt glue, which acts as a light diffuser, mechanical protection of the LED-resistor assembly, and mechanical reinforcement for the cable.

Images


Original connector, power-labeled

Insulation removed

Insulation removed

Resistor and LED in place

Resistor and LED in place

Resistor and LED in place

Resistor and LED in place

Resistor and LED in place

Resistor and LED in place

Molten glue housing

Molten glue housing

Molten glue housing

Lighted up

Lighted up

Lighted up

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