Bench Talk

We built a smart mailbox, as related in an article, that had an ambient light sensor to detect when the mailbox door was opened. In that project we used a Vishay ambient light sensor (Mouser Part #782-TEPT4400) that acts very much like an NPN transistor, in fact the part is also referred to as a phototransistor. The difference being (when compared to a normal bipolar junction transistor) that instead of needing a base lead to setup the bias voltage, photons provide energy at the base-collector junction to turn the transistor on, thus allowing current flow from collector-to-emitter.

When you are just starting off in electronics, there are many design pitfalls that can lead to hours of frustrating troubleshooting. I highlighted the importance of troubleshooting in this earlier blog post regarding my work on the automated energy harvester. Many times these faults are fixed with a very simple tweak to the circuit design or component selection. One of the most basic of the faults is the infamous “floating pin” or “floating input” that can affect the I/O pins of digital integrated circuits.

Working hoverboards have been the subject of many hoaxes for the last few decades; Back to the Future series' director Robert Zemeckis claimed that hoverboards had existed for years, only to be banned by parents groups, to Funny of Die's elaborate and almost convincing prank earlier this year. But now, thanks to Hendo Hover's Kickstarter campaign, this long sought after technology can be in your hands... for $10,000.

Yes, it is possible to burn the $#*&! out of yourself on a resistor….a tiny little resistor. I did this under the supervision of an electronics technician at a bench job I had in college. The tech had hair down to his waist, wore glasses, and confirmed the imagery in Joe Jackson’s lyrics for Soul Kiss: “And all the hippies work for IBM.” As a freshman, I worked in the basement of the Physics department at LSU in the electronics repair shop. I knew nothing. He knew that I knew nothing.

“Do you know what happens when you put a red LED to a 9 volt battery?” This is the first thing the other intern said to me as he walked in this morning. Of course I wanted to see what happened. Knowing that the normal drop for a red LED is about 2.5V, and given the tone of his voice, I knew it would be interesting. Sure enough the LED sheared at the junction. His original plan had been to see if the problem with his tester was the green LED or the switch. He used a 9V battery to test it because it was available. The interesting result was the green LED gave off an orange light. This naturally made him wonder what would happen if he applied 9V to other colored LEDs. Hence the sheared and slightly melted red LED.

Neil Armstrong’s favorite quote was "Science is about what is, engineering is about what can be.” STEM, and now STEAM (Science, Technology, Engineering, Art, and Mathematics) promote these areas for growth. Some might consider the “Art” in STEAM to be out of place, but I disagree. Engineers need cross-pollination, and have you seen some of the incredible art using open source technology?

According to some published studies, the area has the 10th worst traffic in the U.S. and the longest average commute in the US. I have given extensive thought to the social ramifications of self-driving cars. I have thought about this many times before, but now it is personal. The technology used in self-driving cars is fascinating, but I want to talk about the implications.

My family is mildly crazy and the stunt for this past Spring was driving from Los Angeles to Indianapolis in 72 hours. One of my brothers was graduating in Los Angeles and another was getting married near Indianapolis. About 90 minutes out of LA, our car overheated. Naturally my mom and I decided to open the hood and see what we could do. As I poured water over the radiator, I noticed that in some spots the water was boiling on contact and other places it was rolling off and dripping onto the ground. I thought about my thermal class. In particular I was thinking of thermal contact resistance. I recalled a particularly illustrative picture from Chapter 10 of my thermal book and the heat conduction of road dust versus metal (Hint: it is not helping with the heat transfer).

My telecoms class had an end of the year project. You know it is interesting how you do not really think about all you have learned and how fascinating and wonderful it is until the end of the semester. This telecoms project is a great example of making students think about what we learned. It involved suppressing photos and video. We had talked about bandwidth suppression all semester. It made sense. A smaller channel transmitting the same amount of information is always desirable. It was interesting to learn that since our ears, unlike our eyes, are insensitive to phase distortion it is possible to design cheaper filters that allow phase distortion to slip through.

Let’s face it; we’ve all tried to use the wrong tool for the job at hand at least once in our lives. Using a hammer on screws comes to mind as the most common misuse of tools and technology. I will admit it, guilty as charged. Picking the right Open Source Hardware tools and platforms is similar to the picking the right hand tool from our toolbox. Though there is typically enough crossover of functionality between the different types of tools, some are better suited for certain tasks than others. With increasingly more variety of affordable hardware tools coming to market, many makers are starting to ask, “What’s the right tool for the job?”