Hi all, This is my first i'ble and I'd just ask you to please be patient with me if I'm not as clear as experienced users. On to the making, I needed an LED Tester to to check which color it was, if it was infrared, or if it were working. I have a very large range of LEDs kinda lying around which require different voltages so I needed an LED Tester which would work two batteries. For me the convenient ones were a 3V button cell and a tiny 12V battery. You may use any kind of battery you prefer as long as they fit in your casing and can power an LED. Let's get started.

Step 1: Designing the Circuit

After thinking I would need two different batteries, I realised I also needed a switch to choose which battery I'd like to use for each given time. I sketched a simple schematic here which basically uses a switch, female jumper wires, two batteries, and some wire. The switch's opposite pins will be connected to the positives of both batteries, while the middle pin is connected to the female jumper wire. On the other hand, the negatives for both batteries are joined and connected to the other female jumper wire.

Step 2: Fetching the Materials

Materials:

- Casing to fit your project (I used an old Nintendo DS game cartridge case)

- Your Batteries

- A Switch

- Female Breadboard Jumper Wires

- Tape

- Wire

Tools:

- Soldering Iron w/ Solder

- Dremel (I used an old Soldering Iron to melt the plastic)

- Wire Cutters

Step 3: Cutting Out the Ports

I measured the Switch and Female Jumper Wires and marked them on the casing, then cut them out.

Step 4: Soldering to the Switch

Sorry for the blurriness. I then got a female wire and two normal wire and soldered them to the switch as shown and just like the schematic.

Step 5: Ground Wires

After the switch has been soldered to, I soldered two normal wires to a female jumper wire, which were going to be used for the negatives, like so. The two normal bottom wires will connect to the negative sides of the battery and the female port will stick out of the casing.

Step 6: Put It Together

After some soldering, it is time to put it all together. Connect one wire, which is soldered onto the end of the switch, to the positive of one battery and the opposite wire of the switch connected to the positive of the other battery. Then put the female port soldered onto the switch through a hole in the casing. Put the negative female port through the other hole, while the switch is placed in the larger hole.

Step 7: Close It Up

Once your done, shove the wires in there and make sure everything fits and finally close it. I used a sharpie afterwards to label the switch and female ports.

Ta-Da!