Pre-lab: Soldering, Teensy Installation

The questions below are due on Friday February 21, 2025; 05:00:00 PM.
 
You are not logged in.

Please Log In for full access to the web site.
Note that this link will take you to an external site (https://shimmer.mit.edu) to authenticate, and then you will be redirected back to this page.

In this week's lab, we'll be building a really cool circuit. This pre-lab consists of two pieces, designed to help you get ready:

  1. Some tutorial information about soldering.
  2. Double-checking that your Arduino install has all the necessary pieces.

1) Soldering Intro

This lab is going to be our first exposure to soldering (in American English, this word is usually pronounced like "SOD-der-ring" (IPA: /ˈsɒdərɪŋ/); the L is silent). Soldering involves joining two pieces of metal together using solder ("SOD-der"). We'll use a soldering iron like the following to accomplish this:

Note that there is a little stand (on the left) to hold the iron (bottom right), and it connects up via a cable to a little base station (in the middle) where you can turn it on and off or adjust the temperature. The grey pad is the thing you should be holding on to. The metal tip of the iron GETS REALLY HOT (it needs to in order to melt the solder), so be really careful not to touch it.

1.1) Soldering 101

Creating a solder joint involves a few steps:

  • Heat both the part (the pin sticking through) and the pad (the metal contact on the PCB) for 2-3 seconds using the iron, making sure you're in contact with both.
  • Feed a small amount of solder onto the joint. It should "flow" smoothly into place and make a shape like a little pyramid or cone.
  • Continue heating for another second or so, then remove the iron.
  • Let the joint cool before moving things around.

The whole process looks like the following (in real time):

1.2) Common Problems

Adafruit also has a good guide to soldering, and in particular a really nice page showing several common problems and how to fix them. The following picture from that guide is a summary of some common issues:

Again, we're looking for a nice pyramid- or cone-shaped joint.

1.3) Safety

Important Safety Guidelines

Soldering is not edge-of-your-seat daredevil-type stuff, but there are lots of things that can be dangerous here. Be careful, pay attention to what you're doing, and take your time; and we should all have a fun safe time.

Some things to pay attention to:

  • Wear safety goggles at all times when soldering and when clipping wires. Getting solder or flux or small pieces of wire in your eyeballs is not fun and can cause serious damage.

  • The tip of the iron gets really hot. For the love of all that is holy, don't touch it. There's a perfectly-good handle you should use instead. Minor burns can result if you touch the hot part even for a short while, and if you remain in contact with it, those burns can become serious. Seek immediate medical attention if a burn breaks the skin. The parts you're soldering will also stay hot for a while, so be careful when touching them.

  • If you want to, use the little vent fans we have around. The rosin in the solder vaporizes at low temperatures and can cause (usually-mild) eye and respiratory irritation if you're exposed to it for a long time. This is not likely to bother most people especially since we'll only be soldering for a short while; but if you have asthma or are at all concerned about possible respiratory irritation, feel free to use a vent fan; we should have enough to go around.

  • Be really careful with the iron around power cords. If the iron melts through plastic on a power cord, it can cause electric shock.

Did you read and understand the safety warnings above?

1.4) Complete Build

You don't have to watch this if you don't want to, but if you do want to, here is a video showing the complete process of constructing this week's lab project. The video comes in three flavors:

2) Software Installation

It's also worth double-checking that you finished the Teensy installation from last week.

To check, open up Arduino, choose "Teensy 4.0" from the Tools -> Board menu, and then after slecting that, you should see "XInput" as an option under "Serial Type." If you don't see that option, you should go back and re-do step 6 "Add XInput support for Teensy" from this page.