Introduction: AT-ATX – Portable Bench Power Supply (with Voltmeter and USB Hub)
The internet is littered with instructions on how to make a power supply out of a used ATX computer power supply. I was trying to think of a good way to make one portable to take between my work area in the shed, my work area in my computer room, and my work area at the office (which does not normally involve wiring electronics). So I decided I needed a portable power supply, among other things. But I decided to have some fun with the project.
When I first saw people online modifying 1970s Star Wars toys my first instinct was Blasphemy! However, I came to realize there are many many older toys which have been played with, broken, torn apart, and dismantled and will never be collectibles. Modifying them into something usable and cool gives them a second life. That’s my rationale anyway for why I started this project.
I took a vintage At-At from the early 1980s which was in poor shape. I then took an ATX power supply out of an older tower PC. I prepared both for the project.
Step 1: AT-AT
After cleaning the dirt and grime off it, I measured the inside and prepared a new door with slots for wire connectors (technically speaker wire connectors) and a USB drive. I used .60 Polystyrene for the door. When I purchased the At-AT no door was included. After all measurements were done, I spray painted the vehicle a glossy black. I should have probably pained last, but was afraid of getting paint into some of the outside components intended to use.
Step 2: Fan
I cut a 1 ¼ inch hole out of the back in order to place a small PC fan on top for cooling and ventilation. I cut a small hole for a rocker switch and another for the AC power plug. I then cut two small holes in the front underside for two blue LEDs.
Step 3: ATX
I removed the power supply board from the metal casing. It slid nicely into the AT-AT but with not much room to maneuver. I popped the AC plug through the hole in the back. Then screwed the fan on top of the hole, which happened to be right above the heat sink. I needed to use some Sugu around the plug for some extra strength as the plastic around the back was weakened by my cutting.
Step 4: Wiring
I tied one of the black ground wires to the rocker switch and the green to the other side of the rocker to turn power on or off. I wired the fan to the black and red wires the original fan was tied to. I do not know if it has the same power as the black and red from the rest of the black and red, but the wires are smaller and they are connected to a very different part of the board so I decided not to risk it and just tied it to the wires from the original fan. I took an old USB cable from the same computer I took the ATX from and wired it directly to 5V from the supply (connecting black and red). I then glued a cheap USB hub to the bottom of the interior and had a slot cut out of the Polystyrene for its location. I connected the USB hub to the USB cable directly wired.
I then tied the grounds to each of the round wire connectors in the picture. The orange wires are 3.3V and went to one connector, the red are 5.0V so went to two of them. I took the +12 to two other terminals. I then took the +12 and -12 and connected them to the final connector. The thing about doing that is you are not connecting it to ground, but it creates a +24V. I’m not an electrical engineer, but my understanding (from an engineer friend) is that it’s fine to do this to get 24V, but you cannot connect anything to the other power connectors while using it. It apparently can (but not always will) cause a disruption in the phase of the wires if you attempt to use one of the other connections. Not sure exactly what that means, but I normally do not run more than one 24V piece at a time so I haven’t had the occasion to test it to see what he meant.
I use small hinges to attach the door and 20mm Neodymium magnets to help hold the door closed. I placed a magnet inside, behind the wall, then one on the outside of the wall, then one on the underside of the door and a fourth on the outside of the door. This provided a sufficient field to hold the door (pushing back a large number of wires) without using larger magnets which detract from its use (and hopefully not enough to interfere with the electronics).
I cut out a small 2X1.5 inch hole and slid in a small voltmeter. I connected alligator clips to the voltmeter and popped out two holes for the leads. I placed two more magnets in the center of the door (with guerilla glue), one on the inside and one on the outside. The leads can either rest attached to these, or (unexpectedly) still look cool attached to the outer magnets for the door.
I sanded down the edges and used some black rubber to trace around the edges of the USB drive to give it a better look. I used painter tape to cover up the essential components then touched up with spray paint. The paint had built in lacquer else I would have placed a coat of it as well. I wired two blue LEDs (with 33 Ohm resistors tied to 3V) and popped them through the holes in the front undercarriage to give it that awesome blue glow when on, along with the blue LEDs built into the USB hub.
Step 9: Finale
I tried gluing the legs on since having them move is not essential for its use as long as it stands. However, I’m thinking I’m going to need to use some nuts and bolts to properly secure them. If so, I’ll update this instructable.
I now have a fun, cool (in my opinion), but portable power supply to take with me; although it’s not as practical to move around as I could have made it (i.e. in a boring old box). But I like the result.