# Active Discussion About Passive Components

People talk about active and passive components like they are two distinct classes of electronic parts. When sourcing components on a BOM, you have the passives, which are the little things that are cheaper than a dime a dozen, and then the rest that make up the bulk of the cost. Diodes and transistors definitely fall into the cheap little things category, but aren’t necessarily passive components, so what IS the difference?

The best hardware conference is just a few weeks away. This is the Hackaday Superconference, and it’s two days of talks, an extra day of festivities, soldering irons, and an epic hardware badge. We’ve been working on this badge for a while now, and it’s finally time to share some early details. This is an awesome badge and a great example of how to manufacture electronics on an extremely compressed timetable. This is badgelife, the hardware demoscene of electronic conference badges.

So, what does this badge do? It’s a camera. It has games, and it’s designed by [Mike Harrison] of Mike’s Electric Stuff. He designed and prototyped this badge in a single weekend. On board is a PIC32 microcontroller, an OV9650 camera module, and a bright, crisp 128×128 resolution color OLED display. Tie everything together with a few buttons, and you have a badge that’s really incredible.

So, how do you get one? You’ve got to come to the Hackaday Superconference. This year we’re doing things a bit differently and opening the doors a day early to get the hacker village started with badge hacking topped off by a party that evening and everyone coming to Supercon is invited! This is a badge full of games, puzzles, and video capture and isn’t something to miss. We have less than 30 tickets left so grab your ticket now and read on.

# Ben Franklin’s Weak Motor and Other Forgotten Locomotion

Most of the electric motors we see these days are of the electromagnetic variety, and for good reason: they’re powerful. But there’s a type of motor that was invented before the electromagnetic one, and of which there are many variations. Those are motors that run on high voltage, and the attraction and repulsion of charge, commonly known as electrostatic motors.

Ben Franklin — whose electric experiments are most frequently associated with flying a kite in a thunderstorm — built and tested one such high-voltage motor. It wasn’t very powerful, but was good enough for him to envision using it as a rotisserie hack. Food is a powerful motivator.

What follows is a walk through the development of various types of these motors, from the earliest ion propelled ones to the induction motors which most have never heard of before, even an HV hacker such as yours truly.

# Books You Should Read: Feynman’s Appendix to the Challenger Disaster Report

It isn’t really a book, but Richard Feynman’s Appendix to the Challenger Disaster Report is still definitely something you should read. It’s not particularly long, but it’s educational and relevant not just as an example of critical thinking in action, but as a reminder not to fool oneself; neither individually, nor on an organizational level. Sadly, while much was learned from the events leading to and surrounding the Challenger disaster, over thirty years later many of us can still find a lot of the same things to relate to in our own professional lives. There isn’t a single magic solution, because these problems are subtle and often masquerade as normal.

## Feynman and the Challenger Disaster

Richard Feynman (1918-1988) was a Nobel Prize winning physicist and one of the best-known scientists of his time. In 1986 he somewhat reluctantly agreed to join the Rogers Commission, whose task was to investigate the Challenger disaster. The space shuttle Challenger had exploded a little more than a minute after launch, killing everyone on board. The commission’s job was to find out what had gone wrong and how it had happened, and figure out how to keep it from happening again.

# Calculus in 20 Minutes

If you went to engineering school, you probably remember going to a lot of calculus classes. You may or may not remember a lot of calculus. If you didn’t go to engineering school, you will find that there’s an upper limit to how much electronics theory you can learn before you have to learn calculus. Now imagine Khan Academy, run by an auctioneer and done without computers. Well, you don’t have to imagine it. Thinkwell has two videos that purport to teach you calculus in twenty minutes (YouTube, embedded below).

We are going to be honest. If you need a refresher, these videos might be useful. If you have no idea how to do calculus, maybe these are going to whiz by a little fast. However, either way, the videos have some humor value both from the FedEx commercial-style delivery to the non-computerized graphics (not to mention the glass-breaking sound effects). Of course, the video is about ten years old, but that’s part of its charm.

# Network Analysers: The Electrical Kind

Instrumentation has progressed by leaps and bounds in the last few years, however, the fundamental analysis techniques that are the foundation of modern-day equipment remain the same. A network analyzer is an instrument that allows us to characterize RF networks such as filters, mixers, antennas and even new materials for microwave electronics such as ceramic capacitors and resonators in the gigahertz range. In this write-up, I discuss network analyzers in brief and how the DIY movement has helped bring down the cost of such devices. I will also share some existing projects that may help you build your own along with some use cases where a network analyzer may be employed. Let’s dive right in.

# Network Analysis Fundamentals

As a conceptual model, think of light hitting a lens and most of it going through but part of it getting reflected back.

The same applies to an electrical/RF network where the RF energy that is launched into the device may be attenuated a bit, transmitted to an extent and some of it reflected back. This analysis gives us an attenuation coefficient and a reflection coefficient which explains the behavior of the device under test (DUT).

Of course, this may not be enough and we may also require information about the phase relationship between the signals. Such instruments are termed Vector Network Analysers and are helpful in measuring the scattering parameters or S-Parameters of a DUT.

The scattering matrix links the incident waves a1, a2 to the outgoing waves b1, b2 according to the following linear equation: $\begin{bmatrix} b_1 \\ b_2 \end{bmatrix} = \begin{bmatrix} S_{11} & S_{12} \\ S_{21} & S_{22} \end{bmatrix} * \begin{bmatrix} a_1 \\ a_2 \end{bmatrix}$.

The equation shows that the S-parameters are expressed as the matrix S, where and denote the output and input port numbers of the DUT.

This completely characterizes a network for attenuation, reflection as well as insertion loss. S-Parameters are explained more in details in Electromagnetic Field Theory and Transmission Line Theory but suffice to say that these measurements will be used to deduce the properties of the DUT and generate a mathematical model for the same.

# General Architecture

As mentioned previously, a simple network analyzer would be a signal generator connected and a spectrum analyzer combined to work together. The signal generator would be configured to output a signal of a known frequency and the spectrum analyzer would be used to detect the signal at the other end. Then the frequency would be changed to another and the process repeats such that the system sweeps a range of frequencies and the output can be tabulated or plotted on a graph. In order to get reflected power, a microwave component such as a magic-T or directional couplers, however, all of this is usually inbuilt into modern-day VNAs.
Continue reading “Network Analysers: The Electrical Kind”

# Inventing The Induction Motor

When you think of who invented the induction motor, Nikola Tesla and Galileo Ferraris should come to mind. Though that could be a case of the squeaky wheel being the one that gets the grease. Those two were the ones who fought it out just when the infrastructure for these motors was being developed. Then again, Tesla played a huge part in inventing much of the technology behind that infrastructure.

Although they claimed to have invented it independently, nothing’s ever invented in a vacuum, and there was an interesting progression of both little guys and giants that came before them; Charles Babbage was surprisingly one of those giants. So let’s start at the beginning, and work our way to Tesla and Ferraris.