inductance

21 Articles

Cascade Failures, Computer Problems, And Ohms Law: Understanding The Northeast Blackout Of 2003

February 25, 2022 by 16 Comments

We’ve all experienced power outages of some kind, be it a breaker tripping at an inconvenient time to a storm causing a lack of separation between a tree and a power line. The impact is generally localized and rarely is there a loss of life, though it can happen. But in the video below the break, [Grady] of Practical Engineering breaks down the Northeast Blackout of 2003, the largest power failure ever experienced in North America. Power was out for days in some cases, and almost 100 deaths were attributed to the loss of electricity.

[Grady] goes into a good amount of detail regarding the monitoring systems, software simulation, and contingency planning that goes into operating a large scale power grid. The video explains how inductive loads cause reactance and how the effect exacerbated an already complex problem. Don’t know what inductive loads and reactance are? That’s okay, the video explains it quite well, and it gives an excellent basis for understanding AC electronics and even RF electronic theories surrounding inductance, capacitance, and reactance.

So, what caused the actual outage? The complex cascade failure is explained step by step, and the video is certainly worth the watch, even if you’re already familiar with the event.

It would be irresponsible to bring up the 2003 outage without talking about the Texas ERCOT outages just one year ago– an article whose comments section nearly caused a blackout at the Hackaday Data Center!

Continue reading “Cascade Failures, Computer Problems, And Ohms Law: Understanding The Northeast Blackout Of 2003” →

Tonewheels Warble In This Organ-Inspired Musical Instrument

February 10, 2021 by 9 Comments

Younger readers may not recall the days when every mall had a music store — not the kind where tapes and LPs were sold, but the kind where you could buy instruments. These places inevitably had an employee belting out mall-music to all and sundry on an electric organ. And more often than not, the organist was playing a Hammond organ, with the distinct sound of these instruments generated by something similar to this tonewheel organ robot.

Tonewheels are toothed ferromagnetic wheels that are rotated near a pickup coil. This induces a current that can be amplified; alter the tooth profile or change the speed of rotation, and you’ve got control over the sounds produced. While a Hammond organ uses this technique to produce a wide range of sounds, [The Mixed Signal]’s effort is considerably more modest but nonetheless interesting. A stepper motor and a 1:8 ratio 3D-printed gearbox power a pair of shafts which each carry three different tonewheels. The tonewheels themselves are laser-cut from mild steel and range from what look like spur gears to wheels with but a few large lobes. This is a step up from the previous version of this instrument, which used tonewheels 3D-printed from magnetic filament.

Each tonewheel has its own pickup, wound using a coil winder that [TheMixed Signal] previously built. Each coil has a soft iron core, allowing for the addition of one or more neodymium bias magnets, which dramatically alters the tone. The video below shows the build and a demo; skip ahead to 16:10 or so if you just want to hear the instrument play. It’s — interesting. But it’s clearly a work in progress, and we’re eager to see where it goes. Continue reading “Tonewheels Warble In This Organ-Inspired Musical Instrument” →

Otis Boykin’s Precision Passives Propelled The Pacemaker

September 16, 2020 by 11 Comments

The simplest ideas can be the ones that change the world. For Otis Boykin, it was a new way to make wirewound precision resistors. Just like that, he altered the course of electronics with his ideas about what a resistor could be. Now his inventions are in everything from household appliances and electronics to missile guidance computers.

While we like to geek out about developments in resistor tech, Otis’ most widely notable contribution to electronics is the control unit he designed for pacemakers, which regulate a person’s heartbeat. Pacemakers are a real-time clock for humans, and he made them more precise than ever.

Street Smarts and Book Smarts

Otis Frank Boykin was born August 29th, 1920 in Dallas, Texas to Sarah and Walter Boykin. Otis’ father was a carpenter who later became a preacher. His mother Sarah was a maid, and she died of heart failure when Otis was only a year old.

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Solving The Mysteries Of Grounding While Improving A Power Supply

February 4, 2020 by 20 Comments

Grounding problems and unwanted noise in electrical systems can often lead to insanity. It can seem like there’s no method to the madness when an electrical “gremlin” caused by one of these things pops its head out. When looking more closely, however, these issues have a way of becoming more obvious. In a recent video, [Fesz Electronics] shows us how to investigate some of these problems by looking at a small desktop power supply, modelling it in LTSpice, and reducing the noise on the power supply’s output.

While everything in this setup is properly grounded, including the power supply and oscilloscope, the way the grounding systems interact can contribute to the high amount of noise. This was discovered by isolating the power supply from earth ground using electrical tape (not recommended as a long-term solution) and seeing that the noise was reduced. However, the ripple increased substantially, so a more permanent fix was needed. For that, the power supply was modelled in LTSpice. This is where a key discovery was made: since all the parts of the power supply aren’t ideal, noise can be introduced from the actual real-life electrical behavior of some of the parts. In this case, it was non-ideal capacitance in the transformer.

According to the model, this power supply could be improved by adding a larger capacitor across the output leads, and also by increasing their inductance. A large capacitor was soldered in the power supply and an iron ferrule was added, which decreased the noise level from 100 mV to around 20. Still not perfect, but a much needed improvement to the simple power supply. If, on the other hand, you want to make sure you eliminate that transformer’s capacitance completely, you can always go with a transformerless power supply. That carries other risks, though.

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Inductance In PCB Layout: The Good, The Bad, And The Fugly

September 28, 2018 by 39 Comments

When current flows through a conductor it becomes an inductor, when there is an inductor there is an electromagnetic field (EM). This can cause a variety of issues during PCB layout if you don’t plan properly, and sometimes we get burned even when we think we have planned for unwanted inductance and the effects that come with them.

When doing high speed logic we need to be able to deliver sudden changes in current to the devices if we want to have proper switching times and logic levels. Unfortunately inductance is usually not a friend in these circumstances as it resists those sudden changes in current. If the high speed devices are driving capacitive loads, which themselves are resisting changes in voltage, even more instantaneous current is needed.

Simply put, inductors resist a change of current, and can act as a low pass filter when in series with the signal or power supply flow. Inductors do this by storing energy in the flux surrounding the conductor. Alternatively capacitors resist a change in voltage (again by storing energy) and can act as a high pass filter when in series with the signal. This makes them a valuable tool in the fight against unwanted inductance in power supply distribution.

In the video below, and the remainder of this article, I’m going to dive into the concept of inductance and how it affects our design choices when laying out circuit boards.

Continue reading “Inductance In PCB Layout: The Good, The Bad, And The Fugly” →

Adding Analog Touch To (Nearly) Any Mechanical Keyboard

September 26, 2018 by 37 Comments

The new hotness for DIY electronics is mechanical keyboards, and over the past few years we’ve seen some amazing innovations. This one is something different. It adds an analog sensor to nearly any mechanical key switch, does it with a minimal number of parts, and doesn’t require any modification of the switch itself. It’s a reddit thread and imgur post, but the idea is just so good we can overlook the documentation on this one.

The key development behind this type of sensor is realizing that nearly every mechanical keyswitch (Cherry MX, Kalth, Gateron) has a spring in the bottom. A spring is just a coil of wire, and an inductor is just a coil of wire, too. By putting a spiral trace on the PCB of a mechanical keyboard underneath the keyswitch, you can sense the inductance of this spring. This does require a little bit of additional hardware, in this case an LDC1614 inductance to digital converter, but this is an I2C-readable part that can, theoretically, be integrated rather easily with any mechanical keyboard PCB and firmware.

The downside to using the LDC1614 is that sampling is somewhat time-limited, with four channels or individual keys being polled at 500 Hz. This isn’t a problem if the use-case is adding analog to your WASD keys, but it may become a problem for an entire keyboard. Additionally, the LDC1614 is a slightly expensive part, at about $2 USD in quantity 1000. A fully analog keyboard using this technique is going to be pricey.

Right now, the proof-of-concept for this analog mechanical keyswitch is just a 0.1 mm flexible PCB that is shoehorned inbetween a Cherry MX red and a (normal) mechanical keyboard PCB. The next step in the development will be a 2×4 keypad with analog sensors, and opening up the hardware and firmware examples up under a GPL license.

Line Following Robot Without The Lines

August 10, 2018 by 19 Comments

Line-following robots are a great intro to robotics in general, since the materials and skills needed to build a good one aren’t too advanced. It turns out that line-following robots are more than just a learning tool, too. They’re pretty useful in industry, but most of them don’t follow visible marked lines. Some, like this inductive guided robot from [Randall] make use of wires to determine their paths.

Some of the benefits of inductive guidance over physical lines are that the wires can be hidden in floors, so if something like an automated forklift is using them at a warehouse there will be less trip hazard and less maintenance of the guides. They also support multiple paths, so no complicated track switching has to take place. [Randall]’s robot is a small demonstration of a larger system he built as a technician for an autonomous guided vehicle system. His video goes into the details of how they work, more of their advantages and disadvantages, and a few other things.

While inductive guided robots have been used for decades now, they’re starting to be replaced by robots with local positioning systems and computer vision. We’ve recently seen robots that are built to utilize these forms of navigation as well.

Continue reading “Line Following Robot Without The Lines” →