A variable DC power supply is really useful to keep on your desk for charging your phone, plugging in a raspberry pi or any other low voltage electronic devices. By using voltage regulators you can set just the amounts to output, whether you need 3.3, 5, 12 or any other amount. This is a really fun project that you can customize to your needs, varying the amount of plugs, set the voltage, choose the size etc... I used MDF for the build, however you could make a box out of anything really to house the electronics.
Step 1: The Design
So I started with making a sketch of the design. For this build I need to use two voltage regulators, I picked mine up online. I also need a switch, and then I'm going to add a series of outlets that you can plug male pigtails into. Here I'm just confirming the current draw of an LED I want to wire so that I can determine the size of the resistor I need.
Products Used in this Build (Affiliate Links)
- Voltage Regulator for DC Power - http://amzn.to/1mD8Pze
- Pigtail Connectors - http://amzn.to/1PdDx96
- Hot Glue Gun - http://amzn.to/1PdDx96
- Hook Up Wire - http://amzn.to/1PdDx96
- Soldering Iron - http://amzn.to/1PdDx96
- Swtiches - http://amzn.to/1PdDx96
- LED indicator light - http://amzn.to/1PdDx96
So this is kind of the design that I'm thinking. The rectangles in the middle is to show the screens on the voltage regulators, then we have outlets underneath, a switch and a light to signify the unit is on.
Step 2: The Materials
So I'm starting with cutting up the materials for the box itself, and I'm using 1/4 inch MDF.
The final dimensions of the box will measure 8 x 8 x 2 1/2 inches so just cutting up the pieces for that.
Let's dry fit it to make sure everything fits!
Step 3: The Front of the Box
Now let's start working on the front of the box. So first I'm getting the dimension of the plug, setting up a compass. So drawing a circle, then seeing how far I want the outlets apart, and 3/4 of an inch in between each center seems like a good distance. All in all I want eight outlets, so drawing those all out.
Sketching out the space for the switch and the position of the voltage regulators. Also measuring out where the screens are, and where the holes need to go for those on the board, as well as where the little button that changes the output on the screen is located. And there it is, all marked out.
Step 4: Drilling
So I'm starting with drilling out the holes for the outlets using the drill press and a 7/16 inch bit. I'm also drilling holes in the center for where the screens will display to remove some material. And then cleaning up those rectangles with some chisel work.
Also drilling holes for areas that I need to access on the voltage regulators, a hole where you can insert a screwdriver to change the output, and a spot with a button to push to change the display on the screen.
Then doing a little sanding, a little cleaning up with a chisel, and I'm ready to assemble the box together. So measuring out 1/8 of an inch around the top wher I'm going to drill holes to screw it in. Doing some countersinking here.
Step 5: Putting the Box Together
Now to put the box together, I'm starting with yellow glue around the edges, then I'm adding small amounts of hot glue on one piece at a time, because it stiffens up so quickly, and this basically acts as a clamp while the yellow glue dries. It works really well. And then simply screwing the top in place.
Step 6: Finishing the Box
I decided to paint this box white for some contrast, and I'm just using cheap basic white paint here. To paint the inside of those little holes I'm using a small brush. Then once the paint dried I put on two coats of waterbased polyurethane which is nice because it doesn't add a yellow tone and it dries quickly, and of course it adds some additional protection.
Step 7: The Electronics
So real quick, let's go over the electronics here. So I have 20 volt ac dc power supply, first there is a switch, and we have an LED light which I need a resistor for, then this is hooked up to a voltage regulator and that connects to several output plugs.
So soldering a 2600 ohm resistor on the LED light here, and fitting everything in the box. I drilled a hole on the backside too, to connect a plug in to power the whole unit. Then soldering everything together. A lot of people don't like soldering, but it's really easy and fun, plus as you make more projects you get more practice. Just putting the wires into the voltage regulators, putting in the plugs and doing a little more soldering. Hooking this is and making sure it works.
Step 8: Hooking Up the Electronics
So on the voltage regulators there is this potentiometer on top that you can control and change the output. I'm also going to use this small mechanical screw here and enter it through one of the holes I drilled. Then on the regulator there is this little button to change whether to show the voltage output or input on the screen and now when I put the unit up here the screw is right on the button so I can push it to change the screen.
Next I'm hot gluing some wooden dowels in the corners here, and this so I can glue those to the box to secure the board. Then I'm hot gluing the plugs in, the switch, as well as the dowels on the boards.
Step 9: Wires
Now I put together a couple of cords with pigtails on both sides to plug into the unit to power different things, however to protect the wires, I figured why not secure some mason line, which happens to be bright pink with some hot glue. And I'm just adding a little glue, spinning the cord around and so on.
Step 10: Testing It Out
So the device works really well. To alter the voltage output all I do is to insert a small screwdriver into the top hole and turn it to get just the amount I need. And if I want to see what the input is, then I just click the button with the mechanical screw I put in. Now it's ready to use - set it to whatever voltage you need, plug in your phone, your raspberry pi, charge up your bluetooth speaker and so on....
Step 11: Conclusion - Watch the Video!
For a much better point of view, make sure to check out the video including all the steps to build this cool power strip.