20220715 The Ice Blue LED

20220715 The Ice Blue LED

Posted on | No Comments

OK, so I wanted to have something different for my own TR-595E Tricorder. At the top left of the front, the LEDs are either Amber/Orange (ArkysLab) or Yellow (eFX, Master replicas and the rest of Starfleet). So, I wanted to try something a little whitish.

BUT I DO NOT HAVE A 0805 ICE BLUE

So, I want to use Ice Blue. When lit, the LED will give a cyan like colour. Unfortunately, I do not have them in 0805 (2.0mm x 1.25mm) size but larger. I decided to test with the ‘smallest’ suitable SMD LED in my stash, which is the 3014 (3.0mm x 1.35mm).

EDIT: August, 2022
Actually, I have. And it was in another box of LEDs…
But, the middle one might still short out because of the vias there.

This is the size comparison of the three types of SMD LEDs. I chose the 3014 because it has a long rectangle solder pad which i able to fit into the 0805’s solder pads. But because on the the sodler pads D24 has a vias in the middle, it took a few soldering and desoldering, plus lots of solder flux to get it to work.

There is a reason why I cannot use the 1206 (3.2mm x 1.6mm). Its solder pads are too far apart and will have complications when I solder it onto the smaller 0805 solder pad. The 2014 on the other hand, has solder pad which is a long rectangle and so, it will connect to to the 0805 solder pad.

WHAT JUST HAPPENED?

I prepared the board by applying some solder flux. Then I wet (OK, its tinning but with just some modest amount, enough to grip the LED when it is molten) the 0805’s solder pads with some solder. Now, here is the tricky part. I melt one side of the solder pad first and put the SMD LED onto the pad. The LED would not be positioned exactly on top of the solder pad but offset but about half. Then I did the same on the other side of the remaining pad.

Now, this is where thing start to get weird. Because of the hot resin flux (I suppose), the solder on both pads took slightly longer to solidify. And then, it suddenly ‘pulled’ the LED into position! I thought it was a fluke but LEDs on D23 and D25 did just that. That’s capillary action for you.
So, it was kinda fun and all, except D24 which was really the party pooper. Not only did it not light, I had to remove a lot of solder because of the… solder bump. Remember what I said about the 3014’s long solder pad underneath, well, it made connection with the solder bump. This shorted the connection and the LED would not light up.

THE ICE BLUE LEDS IN ACTION

And so, there it is. My version with the Ice Blue LEDs. By my calculation, these LEDs takes in about 3.4volts and 20mA. But because of the 150R current limiting resistor, it is using about 3mA and it is still so bright. Weird.

Oh, I have changed the bottom right LED from orange to Yellow since I had some very old ones lying around.
Anyway, it is done And I am quite happy with it.
Right after the video has been taken, I noticed the same green LEDs on the scanning array (middle) are not lighting up again. It’s late and so, that will be for another day’s own adventure.

THE VIDEO

Posted in A Piscean Works Blog, Electronics, JLCPCB, Modifications, Printed Circuit Board, Sci-Fi, Star Trek, Tricorder.

Leave a Reply