Before I break ground on this, I just want to say...this works in principal, and is not a 100% accurate form right now!  This is my first drawn out electronic circuit, and it is highly based on sath02 5v regulator. I am also just getting into small electronics like this, so again, there are bound to be screw ups. So please, if you know what went wrong where, let me know! I'd love to get this down to the target voltages!

Now, with the explanation of how bad this is, on to what this actually does: this is a duel power supply unit for a miniature bread board built into an Altoid tin. The basics of it are two 2-way switches: one for on/off, the other for 5v and 3.3v. Along with the switchs, there are two LED's, one for each voltage level. However, this is broken somewhere, giving out a 4.3 and a 3.1 voltage levels. But the principal is still sound!

Here is what you'll need
-Altoid tin
-Some perf board
-Two(2) 3m green LED's
-Two(2) 2-way switches
-Miniature bread board (Radioshacks work the best, as they have foam tape)
-Wire (22 gauge will work)
-Four(4) 1N4001 diodes
-78L05 voltage regulator
-78L33 voltage regulator
-100 ohm resistor
-33 ohm resistor
-100 uf capacitor
-10 uf capacitor
-9 volt battery clip
-2-part epoxy or similar glue**

And then some tools
-Soldering iron +stand (just because it's handy to have, and safe)
-Solder pick or similar (really anything to poke holes in metal with)
-Needle nose pliers or tweezers **
-Hot glue gun (with glue, of course)**

**Not needed items, but may prove very useful

Step 1: The Schematic

Here is the schematic I used for this little project. Again, kudo's to sath02 for the original design.

I ended up using two diodes in this after each of the regulators to ensure no backward current damaging them (which may be where the flaw is at)

Step 2: Prep the Tin

First thing to do would be to stick your breadboard on the tin. This will give you an idea of where to poke holes for your wires, LED's, and switches. This will very from breadboard to breadboard, along with switch type to switch type. It goes without saying, you want enough room to work with on the inside of the tine, along with enough room to access the switches.

While were toying with the tin, we might as well get some other bits and pieces mounted in here. Personally, what I did was mount the power leads, switches, and LED's now.

First, go ahead and get the power leads dealt with. Cut your wire, strip it, and bend it as needed. Poke them into the tin, and strip what you need to strip from the inside

The LED's were placed in their holes, and their leads bent to better suit the opening. Once they were shaped, I soldered them together, and also soldered on the resistors.  I didn't actually mount a wire for ground/negative from the LED set until it was in the tin, which lead to some fun times in a small space.

Step 3: Begin the Assembly

This is where all the fun begins. Now that your tin is all set to go, you can start putting things in it. And, of course, the first thing you need is something to make the circuit on. Go ahead and get two chunks of perf board ready: one to mount your circuit on, the other to serve as a barrier between battery bay and jumper cable bay. These will have to fit in the tin, and allow the tin to close.

Once you have the perf board cut, go ahead and build the circuit. Keep in mind, you will want to mount wires to go to the switches, along with tin said wires. With the circuit made, the peak of funness will begin: wiring things together.

Go ahead and wiggle the circuit in place, pulling the wires for the power supply (the ones that go to the board) into the circuit board (if needed) and make sure everything will reach where it needs to. Once you find that special spot, go ahead and break out some glue and glue that sucker in place.

Once the board is in place, and the glue is dry, go ahead start soldering leads from the pre-mounted portions (which, if you followed this step for step, will mean a ground for the LED, two resistors, and five wires) to the board.

Step 4: Polish, Test, and Be Happy!

Now that you have it all wired up, your good to go! You may be concerned about shorting with some of the wires in the tin. If that's the case, you can always fill the area with some hot glue. While you have that glue gun out, go ahead and make sure all the exposed wire bits and solder are covered that are in the battery bay.
<p>Just a note to let you know I have added this ( a year ago ) to the instructable:</p><p> Comprehensive Guide to Electronic Breadboards: A Meta Instructable</p><p>&gt;&gt; <a href="https://www.instructables.com/id/Comprehensive-Guide-to-Electronic-Breadboards-A-Me/" rel="nofollow"> https://www.instructables.com/id/Comprehensive-Gui...</a></p><p>Take a look at a bunch of project involving breadboards.</p>
<p>Awesome! thanks for the heads up! Also, good guide you got going there!</p>
I was trying to check out your project here and was having a little trouble reading the schematic, would it be possible to have bigger labels next to the components? I like the idea of a portable bread board.
<p>Sorry for the late reply! I have Sath02's project linked at the start. He's schematic is much more clear then mine, and mine is a close mockup of his.</p>
First, let's call this dual and not duel. <br>Second, for the circuitry itself: you get the nominal voltages of 5 and 3.3V at the respective output of the regulator. However the diode in series with the output causes a voltage drop of approximately 0.7V (depending on the output current). That's why you are getting 4.3 and 2.6V. However you need the diodes to make sure only one of the LEDs is lit. I suggest using a single adjustable voltage regulator (LM317) and a DPDT switch, one branch for adjusting the voltage and the other for changing the LED color.
<p>Thank you. I'll look into this.</p>

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