DC Power Supply for Saltwater Etching Project

What you see here is a failed attempt to convert an ATX computer power supply into a general purpose DC power supply for benchtop use. After I installed all the binding posts to the chassis and soldered the wires to the posts, as well as a 10 Ω power resistor to act as a load and a secondary switch, I plugged in the power cord and turned on the main switch. Nothing. The fans refused to whir into life as I expected. I tried flipping the secondary switch a few times and suddenly there was a loud popping sound, sparks from the board and the acrid, electrical smell of an exploded electrolytic capacitor. Three hours of work gone up in smoke, literally.

Yes, I know, my floor is a mess.

Fortunately I had another power supply that I had salvaged from an old Cisco router at work (seen above). The output is rated at +5.10V @ 24.0A, +12.10V @ 5.0A, and -12.0V @ 3.0A. I had to unscrew and take out the board to unsolder some of the extraneous wires. Each of the four binding posts has its own color (red, black, yellow, and blue) to match with the color of the corresponding wire. Each post can accommodate a banana plug cable. I ordered all of the parts from Mouser.

You have to be very careful working with power supplies because some of the larger capacitors still carry charge even after the unit is powered off. If you touch a lead on the board connected to the capacitor you can get electrocuted.

I plan on using this power supply for an impending project for etching designs on Altoid tins.

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One Response to “DC Power Supply for Saltwater Etching Project”

  1. […] includes a plastic Brita water filter tank that I found discarded in the sidewalk one day and a modified DC power supply that I salvaged from an old Cisco router. I filled the tank with a gallon of lukewarm water and dissolved about a cup of salt in […]

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