A Cold Solder

Soldering

In this project, A Cold Solder, we were tasked with creating the starlight water design, an eight-point LED star created through soldering. To start off this project, I first watched an Edpuzzle refresher on how to properly solder. The video summarized the essential process of soldering, including how to use the soldering iron, how to apply the solder, and how to solder two wires together. After watching the video, we were allocated two LEDs and two resistors to practice soldering on an old printed circuit board (PCB). I first inserted the blue LED and resistor into random holes in the PCB. Once I applied a small amount of solder onto the iron and rubbed it on the cleaning sponge, I added solder to the holes where the legs were inserted. By flicking up the iron in a swift motion, a "Hershey kiss" shape is formed with the solder; this applies minimal solder while still offering enough support to the components. Next, I used a pair of wire cutters to trim the excess legs of the LEDs and resistors. To do this, I positioned the wire cutter at the base of the component, placed my hand over the board (this will prevent stray pieces from flying out), and cut the legs short.

Starlight Water Design

The starlight water design is a meticulous project that involves soldering an inventory of components onto a printed circuit board (PCB). Constructed of 73 total LEDs, this project tests the precision and attention of the student, in addition to their mastery of the unit's skills. During this part of the unit, our goal was to successfully create the starlight water design by using a teacher-assigned kit and following an instructional video. With the slideshow as guidelines for day-to-day work, we were able to space out our work between the start of the project and the deadline - the daily journal linked at the top of the page displays the process. Below contains a video of the final product working, as well as images:

Before soldering, I first looked through the given component list containing all of the materials. I went through the inventory and accordingly checked off the components after I located them. Following the first part of the video, I soldered capacitor 1 (104 pF), capacitor 2 (10 uF), capacitor 3 (220 fF), the 10k potentiometer, and the 10k ohm resistor onto their locations on the PCB. Once soldered on, I used wire cutters to cut off the excess wires on the backside of the PCB. Then, I moved onto the 10 triodes (9013) labeled Q1-Q10. To prep each component, I carefully pushed the two outer legs forward and wiggled them into the holes. I soldered them just as I did previously, trimming the wires on the backside once I was done.

Here I soldered the two integrated circuits (IC-CD4014 and IC-NE555) and the nine 20- ohm resistors onto the PCB. Before applying solder on the backside of the board, I bent each resistor's legs and pushed them into their respective holes; the 200-ohm resistors belonged to the sections labeled R2-R10. Because resistors do not have polarity, it didn't matter which way I put them in. I did not trim the legs of the integrated circuits because they were naturally short.

The first image depicts the PCB after soldering on the eleven 1k resistors. Just as I did with the 200-ohm, I bent the legs before inserting them into the board and soldering. Once that was completed, I worked on the first ray of LEDs; in this pattern, the board alternates between a yellow and a red LED, with a red LED at the center. I had to consider the polarity of each LED (the longer leg was positive, and the shorter leg was negative - positive = square while negative = circle), as well as ensure that the LED was fully pushed through before soldering. For reference, these LEDs were two-pronged through-hole LEDs. After thoroughly checking the LEDs, I split the legs apart and used a PCB clamp to prop the board up as I soldered. I trimmed the legs once I finished soldering.

Here I continued working on the distinct LED pattern for the starlight water design, focusing on rays 2 and 3.

Here I continued working on the distinct LED pattern for the starlight water design, focusing on rays 4 and 5.

Here I continued working on the distinct LED pattern for the starlight water design, focusing on the last three rays and the center nine.

Problems Encountered and Solutions

• The only issue I encountered was the LEDs not being pushed all the way through. Before I soldered LEDs onto the board, I inserted the legs and separated them, holding the LEDs still while I soldered. Despite doing this, many of the LEDs became loose and ended up not being pushed all the way through - others became slightly crooked, though none of the mistakes were hugely noticeable. To solve this issue, I made sure to more carefully check the legs after splitting them. This ensured that the LED would be better fastened when I soldered.