To save time, breadboard pins or just lack of knowledge people try to skip adding eve one decoupling capacitor to a circuit. Either on IRC or in Forums you can almost always see it coming: “randomly, my circuit stops working” And then, “what do you mean a decoupling capacitor?” question.
While working on breadboard Arduino, I came across some unexpected measurements. Initially, the only capacitors on the breadboard were the two 22pF from crystal to ground and the capacitor connected to RESET for Auto-RESET.
Keep reading to find out what happen when I added a 100nF and a 1µF cap. A bunch of scope traces and surprising results follow.
Breadboard Arduino with no Decoupling Cap
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Whether you are an engineer with enough experience to be called a graybeard or a novice that keeps grabbing the wrong end of a soldering iron, there is one component that eludes everyone working in electronics.
It’s the humble capacitor.
A seemingly simple device, turns out, to be incredibly complex. While the basic electrode-dielectric-electrode structure sounds simple, the materials used in that structure drastically changes the characteristics of the device.
There’s a new website created by KEMET Electronics which aims to educate all levels of engineers about the ins and outs of capacitors. They call it the KEMET Engineering Center.
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Fun with the meme generating. When it comes to adding decoupling caps, Make It So.
I was invited to speak at the 11th Hardware Developers Didactic Galactic group at the Supplyframe office in San Francisco. I talked about the misconception that capacitors are a simple device.
Chris Gammell recorded the discussion and posted it via PHY Media. This video is about 50 minutes.
In this talk, I break down a few things to know about Ceramic, Aluminum, Tantalum, and Supercapacitors. You can see the full video via PHY Media’s YouTube Channel: They’re JUST Capacitors. For links and the slides, check out this post.
November 2013’s issue of Electronic Products features an article on the cover titled “Introduction to Polymer Capacitors.” The author is, well, me. This article explains the differences between traditional MnO2-Tantalum and Polymer-Tantalum capacitors. Previously I explained these differences in the post on the fire hazard the Arduino GSM shield poses (due to improper derating).
You can find the Electronic Products article wherever magazines are sold or here: Introduction to Polymer Capacitors. Check below for links to high-resolution pictures.
Super excited that I’ll be speaking at this month’s Hardware Developers Didactic Galactic (HDDG) #11. The meetup is on Thursday, February 18, 2016. It should come as no surprise that I’ll be talking about capacitors–something I have a bit of experience on.
Also presenting will be SnapEDA CEO’s Natasha Baker. I’ve written about SnapEDA in the past post, How to find Parts for your Electronics.
One reason to come is just to see what the Hackaday / Supplyframe office looks like!
It is commonly known that ceramic capacitors change capacitance with applied voltage. What isn’t always as well known is how strong this effect can be and why it occurs. At KEMET we’ve put together a technical video that answers that question.
What is Ask An FAE?
Ask An FAE is a new video series we launched at my day job, KEMET. An FAE is a field application engineer. These engineers are very common in the electronics industry. Companies like KEMET, where I work, have FAEs who meet with customers to answer technical (and very detailed) questions about how to use their products. In UBM’s Mind of an Engineer survey, FAEs were ranked as one of the top information sources for design engineers.
At KEMET we decide to use FAEs to answer the questions. While I’m not an FAE today, I was in the past and happy to kick off the series with our CEO.
Check out KEMET’s Ask An FAE
What are aluminum polymer capacitors? These are a solid type of capacitor that replaces the liquid electrolyte with a solid polymer material. Sometimes you might hear these capacitors called “organic aluminum.” Technically, they are still “electrolytic” capacitors. However, the colloquial term of “aluminum electrolytic” refers to the traditional wet electrolyte-based capacitors.
In this video, I meet with Amelia Dalton of EE Journal, and we discuss these capacitor types. Mouser and EE Journal developed the video in joint with KEMET. (Previously I talked on Amelia’s Chalk Talk about SSD Capacitors.)
For me, the release of this video is bittersweet. It is one of my last projects before my departure from KEMET. However, I am excited to talk about aluminum polymer capacitors because they represent one of the “newer” technologies when it comes to capacitors.
Difference between Aluminum Polymer Capacitors and Aluminum Electrolytics
As mentioned, the key difference between the capacitor types is the electrolyte. In a traditional aluminum electrolytic, there is an electrolyte that connects the cathode plate of the capacitor to the cathode electrode. In a polymer capacitor, a solid conductive polymer material replaces the wet electrolyte. The most common polymer material is PEDOT. The use of this material provides an exceptionally low ESR which makes the capacitors can handle more ripple current. Also, because there is no electrolyte to “dry up” or “wear out,” the operational lifetime of these capacitors is much longer. Overall, aluminum polymer capacitors are an excellent alternative to traditional electrolytics.
Learn about Aluminum Polymer Capacitors
Electronics Weekly has invited Dale Cigoy of Keithley Instruments to talk about how capacitors work. Since capacitors are part of almost any Electronic circuit or project, it is a good idea to understand these basic components a little more. The article is titled “Seeing how capacitors work is invaluable.”
Tantalum is a really misunderstood capacitor. Well, all capacitors are misunderstood, but that’s a subject for another post. I ran across this post on the Arduino forums on the Arduino GSM shield. In the post, ddewaele, reports that the shield blew up, catching fire. At first some might think it was due to abuse by the user. While it is possible that reversing the polarity or applying over-voltage could cause a catastrophic failure, it is also possible that the user doing nothing wrong could result in the same failure mode!
Wait, what? So what gives? Well, there’s two things to understand. First, Tantalum doesn’t explode. It takes almost 2000°C before Tantalum metal will ignite. Okay, so if Tantalum doesn’t explode what is ddawaele seeing? It’s the cathode material, Manganese Dioxide, (MnO2) that is exploding…
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Hardware Developers Didactic Galactic is a group for hardware designers, hackers, and enthusiast to discuss hardware-related topics. HDDG11 (or 0xb) featured a presentation from SnapEDA CEO on Footprints and my presentation on Capacitors.
Titled “They’re JUST capacitors?” I used content from my time as a KEMET Field Application Engineer.
In the presentation I address the common myth or guideline: “capacitors should be derated 50%.” Comparing Aluminum, Ceramic, and Tantalum we discuss why each technology has a de-rating associated with it. Turns out, they all have different reasons to de-rate.
Additionally I give a brief introduction to Supercapacitors. (You’ll note that it is spelled with one word…) The key to understanding what makes them “super” relies on how they achieve the common capacitor structure of electrode plate, dielectric, electrode plate.
Download PDF (11mb)
Tools mentioned at the HDDG11 Presentation
Questions related to capacitors or this content, should be asked through the KEMET’s Contact Us.
Understanding what X2 or Y1 capacitors actually are and are not is important when designing them into an AC-mains connected power supply. Recently Electronic Products Magazine ran an article I wrote on the proper role of X and Y safety rated EMI Capacitors.
The X2 capacitor rating means different things to different people–except for UL. When I wrote this article to discuss some common misconceptions around what X2 Rated Capacitors are, and how they can be properly used.
In case the PDF reader doesn’t load, it’s on Page 20 of the November 2014 issue.
You can see the full article with the EP Reader, by clicking here.
A question came up on IRC regarding how to PWM a 3-pin PC fan with an Arduino using analogWrite(). Controlling the fan was seemingly straightforward. The problem was that the hall effect sensor, or TACH signal, was incredibly noisy. The noise made it impossible to measure the fan’s rotation. Working through the question, I found three issues to tackle:
- You need to use a PNP transistor
- Filter capacitors help
- Create a non-blocking RPM measurement (with millis())
This post addresses all three issues regarding how to PWM a 3-pin PC fan with an Arduino.
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When working with components like capacitors and inductors it is always helpful to know how to calculate a resonant frequency. This Resonant Frequency Calculator is an excellent resource because it allows for calculating for Frequency, Inductance, or Capacitance. Sometimes plugging in what you know is faster than working through some algebra.
Check out the: Resonant Frequency Calculator.
The awesome hosts on The Engineering Commons (TEC) podcast asked me to join them on Episode 93-Capacitors! They told me I was the first passive component expert they had on their shown. It was a blast talking to Jeff, Carmen, Brian, and Adam.
The unique thing, in my opinion, about The Engineering Commons is that it covers multiple engineering disciplines. A couple of episodes ago, they talked traffic. Since I am about to move, the episode on Garage Setups was great.
When I put together my list of 5 electrical engineering podcasts, I didn’t include TEC. Which was tough because it is a great podcast, and worth adding to your favorite podcatcher.
If you want to hear my answers to some common capacitor questions, check out The Engineering Commons Podcast Episode 93: Capacitors. For a more in-depth interview, don’t forget about The Spark Gap Episode 25 where I go into a bit more detail about capacitor types.
||October 15, 2015
||Capacitor Interview on The Engineering Commons Podcast
||The Engineering Commons
In this video, I discuss considerations for SSD Capacitors, with a focus on enterprise applications. (No, not the ship kind, the business kind.) As more consumer devices use solid state technology, it gets easier for us to forget the importance of keeping data safe during storage. While solid state drives are more robust than their spinning counterpart, they are not perfect. Just like with spinning drives, there is a small delay from when a write occurs until the data is stored permanently. The highest performance solid state drives parallelize data in a way to minimize this propagation time. However, these drives also keep an active copy of the allocation table in RAM.
Just like the RAM in a PC, when power is lost, so are the contents. So it is critical for a solid state drive to have a reserve bank of energy to dump the RAM contents into permanent storage. Modern drives use huge banks of capacitors to write out any RAM buffers when the system’s rail voltage suddenly disappears.
Learn how to choose Enterprise SSD Capacitors in the EE Journal Chalk Talk.
This video was created in cooperation with KEMET Electronics, Mouser, and EE Journal.
Article I wrote on some innovations KEMET has implemented in their capacitors:
“There is no Moore’s Law for passive components like capacitors, but relentless development is delivering the kinds of devices engineers need to deliver cutting-edge new products for modern living. Capacitors have for many years enabled electronic designers to manage energy within circuits and fulfill basic functions like filtering noise or harmonics, correcting power factor, stabilizing feedback circuitry, coupling/decoupling, interfacing between voltage levels, and storing energy. But the demands placed on these components continue to increase, as electronic devices are expected to be smaller, longer lasting, more feature rich and more robust.”
Read “Capacitor Innovations Address Emerging Opportunities” on Power Systems Design.
||December 30, 2014
||Capacitor innovations address emerging opportunities on PSD
||Power Systems Design
If I were a professional actor, I would feel typecast at this point in my career. Whenever someone wants to talk about Arduino, Oscilloscopes or Capacitors, they call me! In this case, element14 asked me to do two videos on how to replace multilayer ceramic capacitors (MLCCs) with Polymers.
Polymers are an interesting capacitor type. What is usually called a “polymer” is better a called a “polymer electrolytic.” The reason for that detail is the word “polymer” describes the cathode layer and not the dielectric.
For more details, why not check out this episode of element14 Presents’ The Learning Circuit! If you have questions about these capacitors, head over to element14 and leave me a comment there.
e14’s TLC #40
Capacitor lifetime depends on the materials
Although not all applications are safety critical or mission critical, reliability is still a vital consideration for many electronic products. Making informed choices at the part selection stage can help ensure the product will perform correctly over its intended lifetime.
When choosing capacitors, properties such as volumetric efficiency, frequency stability, temperature rating or equivalent series resistance are often the primary factors that govern technology choice. In these cases, understanding factors affecting lifetime can help engineers make sure the product will deliver the required reliability.
On the other hand, a long operational life may be an essential requirement of the end product.
Continue Reading the full article, “Capacitor reliability can be improved with the right materials,” on Electronics Weekly.
||September 28, 2015
||Capacitor reliability can be improved with the right materials
Karl and Corey run The Spark Gap Podcast which is focused on embedded electronics. On Episode 25 they interview me about Capacitors. We covered all the major types of caps, plus some application bits. Check out their show notes for an impressive array of links on the subject.
Also, my favorite episode of theirs so far is episode 18. The guys talk about different serial protocols like SPI, I2C, CAN, etc. Really good stuff.
||January 28, 2015
||Capacitor Questions Answered on The Spark Gap Podcast
||The Spark Gap Podcast