JJ Abrams Tricorder 003

PREPARING THE LEDS

The next thing that needs to be done is the assembly of the custom Blue/Yellow LEDs. As I have mentioned before, the measurements of the LEDs were enough to fit into the cut hole. Provided that they are placed very closely to each other, something which is a bit difficult as the custom LEDs have their first and third leds moulded very close to the edge. In other words, they could short each other out if you're not too careful. Once you get the idea, you can do the same for the three green LEDs as well. Make sure their Ground legs are oriented towards the Blue/Yellow LEDs's Ground rail.

Place the custom Blue/Green LEDs side by side, using a 1mm black double-sided tape to hold them all together. Try to make the gaps between each LED less than 1mm. Oh, make sure the legs for each LED colour is on the correct side. You can do this with a Multimeter, set to x10 Ohm (or 15mA) resistance test.

 

Now, (in my case) lift the middle legs of each LED upwards. Using a pair of long nose pliers, bend them to the right after the 3mm mark. Then solder them into one long rail. This is to create the common Ground for the LEDs. Bend the excess bundle into a 90º angle. At this moment, leave the other two legs alone.

 

Finally, gently press the whole Ground assembly towards the LED body. This would not only create a common Ground for the LED array but also, indirectly strengthen the whole array (in theory, this would never work) apart from the double-sided tape. So, now I have 5 less connections to solder.

 

 

POSITIONING THE LEDS

There is a reason why I used the double-sided tape. They are to hold the LEDs in position while the hot glue sets and hardens. The problem here is that there is limited space in the toy and these LEDs are actually too big. Moreover, I cannot just call up the manufacturer and ask for 10 SMD version. And so, I have to make sure that the green flap switch from the circuit is still able to sit flush with the plastic. If it comes out too much, even by 1mm, the switch will never work. So, while the hot glue is still setting, gently use the flap switch and push it in for a test fit. Never mind if the last LED juts out as they will be grinded off anyway.

Now, slowly insert the whole array into the cut hole. I inserted the array from the front as this is the easiest route for me. Once they are in position, peel the double-sided tape's protective cover off. In the meantime, warm up your hot-melt glue gun.

 

Use the hot melt glue and fix the LEDs into place. And do not forget to test fit the green flap switch. When the glue hardens, you have a very hard time correcting this error. And chances are, you might melt more than just glue.

 

 

WIRING

By now, you would have realised that each dual-colour LED needs three circuit connections. And so, in total, we're looking at a minimum of 24 soldering points. But because I have soldered the Ground legs for both the dual-colour and the green LEDs, I now have 14 points to solder instead. This time, I am using the wire-wraping wires as ordinary wires are too thick. But there is a catch. They are very fragile and are likely to snap off or create a short if you're not too careful. One thing I have learnt about these wires are that you cannot strip them with anything other than melting the plastic sheath off. The reason is,  if you use a blade or a wire-stripper, their sharp blades actually create a small dent in the wire. Over time, when you flex the cable (even of you're not doing anything) or when it moves, the wire will weaken and eventually snap off. So, the only way is to use a soldering iron. Use the tip to melt the plastic sheath off and then get some solder to coat the ends. Once you have solder the wire to your points, quickly secure it with epoxy or a quick dab of hot glue so that it does not move much. But do leave some extra length in case they do snap off unexpectedly.

It does help to have some wire-wraping wires in different colours. And also discipline yourself what each colour stands for, i.e. Black for Ground, Red for Power, Blue for I/O and so on. They're expensive but worth it.

 

In order to ensure the legs of each LEDs are not shorting the next one, I used heat-shrink tubing. Gently force them in between and use the soldering iron's tip to brush against the tube. The heat will shrink the tube.

 

Its also a good idea to label each cable in case you cannot finish it today. When you come back to it later, the labels really helps a lot. Never pull or stress the wires as they will have their revenge when you least expect it. Also, do label the wires, ya?

 

 

 

 

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