Kibbles & Bytes Blog

  • _Hello Fellow Technophiles,_

    I have made it back from Florida safe and sound. I am confused about all of this white stuff on the ground that does not appear to be sand, though. It’s cold, wet, and it’s everywhere. As a lifelong Vermonter, I am not sure that it was wise to experience 75 degree days in February because before this trip I just took winter as something that is inevitable and must be endured. I have heard that after the Civil War a significant number of Union soldiers from Vermont stayed down south, which up hear means anywhere south of the Vermont/Massachusetts border.

    I hadn’t flown JetBlue in a while and was pleased to discover that in addition to TVs in every seat, they now also offer free gate-to-gate wifi. It is becoming increasingly rare, even in the wilds of Vermont, to be out of a coverage zone, so it made me happy to be able to stay connected even in the air. I want to assure you, however, that I left my phone in the condo most of the times that I went down to the beach and managed to enjoy the sun and surf without distractions from the outside world.

    Thanks for reading!

    Mike
    “*michaeld@smalldog.com*”:mailto:michaeld@smalldog.com

  • Apple Re-Paves The Street

    After several quarters of top-line revenue stagnation, Apple rebounded in the holiday quarter by returning to growth and posting their best financial results…

  • I am heartened by the overwhelming response to the executive order on immigration. Unless you are a native American, you are descended from immigrants. I know I am as my grand parents immigrated to the USA to escape persecution. And do not forget that son of a Syrian immigrant by the name of Steve Jobs! It is wonderful to see the peaceful non-violent demonstrations and the statements by Apple and other businesses including Budweiser who is airing an immigration-themed Super Bowl commercial.

    Small Dog Electronics recognizes the intrinsic value of our immigrants and the diversity that makes our country strong and abhors the misguided executive order.

    Thank you for reading this issue of Kibbles & Bytes!

    Your Kibbles & Bytes Team,

    _Don, Emily & Hadley_

  • Infinite Power

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    I received an interesting question from a reader after my last article and I thought that I’d share it and explain in more detail here.

    The question was about the recommendation that an inverter (or indeed, any power source) have a large amount of excess capacity if being used to run electric motors. For example, if you had an electric motor that required 100 watts, you might need a power source that could supply 300 watts, or more. This oversizing of power sources when it comes to electric motors is almost always true, and the reason why touches on many things I’ve discussed in articles before.

    All electric motors (AC-induction or DC-brushed/brushless) share at least one thing: coils. These coils are what get energized by the electricity, thereby creating a magnetic field, thereby interacting with either a squirrel cage, or permanent magnets, and resulting in motion. If you really break it down and unwind the hundreds of feet of wire coil, the actual electric motor circuit becomes counterintuitively simple. It’s quite literally just a really long wire loop that we are passing power through. In the simplest form, there are no components in the circuit at all. No resistors, no capacitors, nothing. It’s just power applied to a wire loop. This is often called a short circuit. When power is applied to this uncoiled wire, there is no resistance (other than the wire itself), so the current can just flow at maximum unimpeded. Assuming an unlimited power source, the wire itself will eventually become a resistor (through resistive heating) once the current becomes sufficiently high, thereby preventing any kind of runaway situation. Nevertheless, the amount of current that initially flows through that wire loop (the first few milliseconds) can be immense. All inductors including the electromagnets in electric motors, are subject to this phenomenon.

    But we know that electric motors 1) don’t consume infinite amounts of electricity and 2) don’t get super hot from resistive heating. This is because electric motors are also subject to something called **back-EMF** or **counter-EMF**. The EMF stands for ElectroMotive Force. Once an electric motor is spinning, a secondary electromotive force is created that is opposite in direction to the primary electromotive force (the one created by us applying power to the coils). This counter electromotive force interacts with the coils creating the primary electromotive force thereby putting downward pressure on the amount of current flowing through them. This is what ultimately prevents the runaway situation described earlier. However, this counter electromotive force is only present once the motor is up to speed, and its magnitude is directly proportional to motor speed. So when the motor is at a dead stop and power is applied, at that instant, there is NO counter electromotive force, and the motor/coils experience what is called “inrush current”. All inductive (and often capacitive) devices are subject to this inrush current and many are engineered with mechanisms to limit the amount of inrush current so that nothing is damaged. But they only limit it, they don’t typically eliminate it. Therefore, when you power up an electric motor, it may initially (for anywhere up to a few seconds) require more power (sometimes much more) than it would normally consume. A similar phenomenon occurs (in a more controlled fashion) if a load is placed on the motor causing it to slow down. Less rotor speed = less counter-EMF = more current flowing through the coils = more power being used.

    An unloaded electric motor, of any size, only consumes just enough power to overcome the counter electromotive force and the friction of the bearings. You’ve actually probably observed effects of counter electromotive force. If you turn on a large electric motor, such as a drill press, circular saw, etc near an incandescent light, you may notice the light dim very briefly when you turn the device on. This is because the motor is not turning yet, and the amount of power it is consuming is very high, thereby causing a brief voltage drop for lights on the same circuit. Devices with large capacitors such as amplifiers can also experience large inrush current. My friends all used to laugh at my old Pioneer SA-8500 (a mere 60-watt per channel amplifier) because when you turned it on, the lights in the house dimmed briefly. Again, this is because the large capacitors in the amplifier need to fill up, and they do so rapidly.

    This is why if you’re using a finite power source, such as an inverter on a battery, you need to oversize it relative to the motor you’ll be powering. You need to be able to supply that extra power initially to get the motor started. This isn’t to say that household power from the power company is infinite, but it’s a lot harder to drain all of the power from a regional nuclear plant or hydro station.

  • Black History Month – Frederick Douglass

    We are celebrating Black History Month all of February and today we will honor the memory of Frederick Douglass, a former slave that devoted his life to the abolition of slavery.

    Born into slavery, Frederick Douglass became one of the most respected orators and intellectuals of the time, advising Presidents on abolishing slavery, women’s rights and other topics.

    Frederick Augustus Washington Bailey was born into slavery in Talbot County, Maryland, around 1818.

    Frederick Douglass was given to Lucretia Auld, the wife of Thomas Auld, following the death of his master. Lucretia sent Frederick to serve her brother-in-law, Hugh Auld, at his Baltimore home. It was at the Auld home that Frederick Douglass first acquired the skills that would vault him to national celebrity. Defying a ban on teaching slaves to read and write, Hugh Auld’s wife Sophia taught Douglass the alphabet when he was around 12. When Hugh Auld forbade his wife’s lessons, Douglass continued to learn from white children and others in the neighborhood.

    It is easier to build strong children than to repair broken men.

    It was through reading that Douglass’ ideological opposition to slavery began to take shape. He read newspapers avidly, and sought out political writing and literature as much as possible. Hired out to William Freeland, he taught other slaves on the plantation to read the New Testament at a weekly church service. Interest was so great that in any week, more than 40 slaves would attend lessons. Although Freeland did not interfere with the lessons, other local slave owners were less understanding. Armed with clubs and stones, they dispersed the congregation permanently.

    In 1833, Thomas Auld took Douglass back from his son Hugh following a dispute. Thomas Auld sent Douglass to work for Edward Covey, who had a reputation as a “slave-breaker.” Covey’s constant abuse did nearly break the 16-year-old Douglass psychologically. Eventually, however, Douglass fought back, in a scene rendered powerfully in his first autobiography. After losing a physical confrontation with Douglass, Covey never beat him again.

    Frederick Douglass tried to escape from slavery twice before he succeeded. He was assisted in his final attempt by Anna Murray, a free black woman in Baltimore with whom Douglass had fallen in love. On September 3, 1838, Douglass boarded a train to Havre de Grace, Maryland.

    Eventually Douglass was asked to tell his story at abolitionist meetings, after which he became a regular anti-slavery lecturer. William Lloyd Garrison was impressed with Douglass’ strength and rhetorical skill, and wrote of him in The Liberator. Several days after the story ran, Douglass delivered his first speech at the Massachusetts Anti-Slavery Society’s annual convention in Nantucket. Crowds were not always hospitable to Douglass. While participating in an 1843 lecture tour through the Midwest, Douglass was chased and beaten by an angry mob before being rescued by a local Quaker family.

    In addition to abolition, Douglass became an outspoken supporter of women’s rights. In 1848, he was the only African American to attend the first women’s rights convention at Seneca Falls, New York.

    No man can put a chain about the ankle of his fellow man without at last finding the other end fastened about his own neck.

    Elizabeth Cady Stanton asked the assembly to pass a resolution stating the goal of women’s suffrage. Many attendees opposed the idea. Douglass stood and spoke eloquently in favor, arguing that he could not accept the right to vote as a black man if women could not also claim that right.

    By the time of the Civil War, Douglass was one of the most famous black men in the country. He used his status to influence the role of African Americans in the war and their status in the country. In 1863, Douglass conferred with President Abraham Lincoln regarding the treatment of black soldiers, and with President Andrew Johnson on the subject of black suffrage.

    Frederick Douglass was appointed to several political positions following the war. He served as president of the Freedman’s Savings Bank and as chargé d’affaires for the Dominican Republic. After two years, he resigned from his ambassadorship over objections to the particulars of U.S. government policy. He was later appointed minister-resident and consul-general to the Republic of Haiti, a post he held between 1889 and 1891.

    Douglass became the first African American nominated for vice president of the United States, as Victoria Woodhull’s running mate on the Equal Rights Party ticket in 1872. Nominated without his knowledge or consent, Douglass never campaigned. Nonetheless, his nomination marked the first time that an African American appeared on a presidential ballot.

  • Apple Re-Paves the Street

    After several quarters of top-line revenue stagnation, Apple rebounded in the holiday quarter by returning to growth and posting their best financial results ever. That is a statement in and of itself. Apple has posted some pretty spectacular numbers but this was the best. Apple reported revenue of $78.4 billion and net quarterly profit of $17.9 billion, or $3.36 per diluted share, compared to revenue of $75.9 billion and net quarterly profit of $18.4 billion, or $3.28 per diluted share, in the year-ago quarter. Both revenue and earnings per share were company records.

    The so-called expert analysts were calling for sales of $77.4 billion and $3.23 per share profit so Apple handily crushed the street.

    To put this is some context, Adrian Kingsley-Hughes calculated that Apple sold 798,877 iPhones a day during the 98 days of the quarter. That is 33,286 each hour or 554 per minute or 9 iPhones each second. All at an average sales price of $695. He also calculated that amounts to about 39,000 metric tons of iPhones. At 100 metric tons per FedEx flight that’s about 400 flights.

    That’s just iPhone. Apple Services, Mac and Watch businesses all posted all-time record sales. The App store saw $3 Billion in sales in December, alone! Apple Pay users tripled and Apple saw hundreds of millions of Apple Pay transactions in December.

    Mac sales also were very strong with 5.4 million Macs sold this holiday quarter and $7.2 billion in revenue, despite widespread shortages of the new MacBook Pro Touch Bar models. The only negative part of their results was a continued decline in iPad sales at 13.1 million units. I think the iPad is a bit different in terms of the upgrade cycle than an iPhone, hence the softness. I know I don’t trade my iPad often but always want the latest iPhone.

    Apple’s cash stash was $246.09 billion which if that was its own public company would be the 13th largest in the world. With the new administration in Washington, repatriating that cash might be a reality this year.

    “We’re thrilled to report that our holiday quarter results generated Apple’s highest quarterly revenue ever, and broke multiple records along the way. We sold more iPhones than ever before and set all-time revenue records for iPhone, Services, Mac and Apple Watch,” said Tim Cook, Apple’s CEO. “Revenue from Services grew strongly over last year, led by record customer activity on the App Store, and we are very excited about the products in our pipeline.”

    The greatest story in business history continues with these phenomenal results. Congratulations to Tim Cook and the entire Apple team.

  • The big annual craft fair is this weekend here in Key West. Grace and I always go and look but have never bought anything. Maybe this year.

    My little Olde English Bulldogge, Jezebel, is growing up fast. I had a dog trainer come over to give us some tips. The guy was HUGE, no wonder the dogs listen to him. He did have some good ideas and step by step Jezebel is getting to be a good dog. Now, if she would just stop waking me up every day at 3:30AM to go outside.

    I am having fun with all this home automation stuff and I will be changing out my thermostat and locks for HomeKit gear so I can get some first-hand experience. Some of my hippy friends laugh at me for all the automation but I like using technology and it is very nice to know that you can set up “scenes” so you can tell Siri you are going to bed and the lights get turned off, the door is locked and the thermostat is turned down.

    Thank you for reading this issue of Kibbles & Bytes!

    Your Kibbles & Bytes Team,

    Don, Emily & Hadley

  • If the Sine is Pure

    I recently decided to jump start an old hobby of mine: sewing. When I was about high school age I used to sew lots of things, generally by hand. I had learned how to use a sewing machine in school, but my mom didn’t like me using hers, so I generally did small projects only. I made some little velcro-closure sacks for my marble collection, lots of pillows and other stuff along those lines. I would frequently repair tears in clothes when I was in high school by hand, because I didn’t like clothes shopping and that was a way to avoid it.

    It had been my goal for a few years now to learn how to make my own clothes. I decided this was the year and picked up a sewing machine for myself. It took a little bit of doing, but most things came back to me. But what does this have to do with electronics, or anything?

    My solar power station sits underneath my kitchen table, and that’s where I set up my new sewing machine. “Should I try to run my sewing machine off the power station?” I actually ask this question a lot when I have some device in my house. It’s fun to be able to run full-size, useful things off of power you generated yourself.

    The first question I have to ask is, “do I have enough power to run this device?” This question is generally pretty easy to answer. The inverter on my station converts the DC power from the battery to 120VAC that’s as good as (likely better than) regular household power. Inverters are rated for how much power they can deliver. Often they have two ratings that describe how much power they can supply continuously, and how much power they can supply in a quick burst. My inverter is rated for only 300 watts, and I have it set up to trip a breaker over about 200 watts. Most sewing machines are primarily electric motors (induction motors) and maybe a small LED light and digital display. This won’t approach 200 watts, so I’m safe.

    The next thing I have to ask is, “what is the nature of the load being powered?” By this I’m distinguishing between different kinds of loads. There are two main loads you’ll encounter: resistive loads and inductive loads. Resistive loads are very straightforward and easy to understand and identify. Any device that uses electricity to create heat, either as a primary function or byproduct will be a resistive load. Inductive loads can be a little harder to identify, but generally anything with any kind of electromagnet will be an inductive load.

    Clothing iron? Has a heating element, no moving parts, purely resistive load.

    Desk fan? Has moving blades run by an electric motor. Some resistive heating in the motor coils, but primarily inductive.

    Can you guess what kind of load my sewing machine is? Hopefully you said ‘inductive’. In my particular case, the type of load I’m running on my power station doesn’t matter, but there are plenty of cheaper inverters out there that can cause inductive loads to perform poorly, or even damage them. The reason for this is because cheaper inverters create something called a modified sine wave. Hopefully we remember that AC power alternates in the form of a sine wave. A true sine wave is perfectly smooth. A modified sine wave will look like little staircases going up and down ??approximating?? the shape of a sine wave, but not perfectly.

    For a lot of equipment, a modified sine wave will be fine, but some things especially inductive loads, often depend on a clean sine wave. For something precise and expensive like my sewing machine, I’d never want to run it off a modified sine wave. Fortunately, because my inverter is a more premium pure sine wave inverter, I don’t have to worry. Plus the best part is that I get to say I made my first shirt off of 100% solar power!

  • Elgato Eve

    I continue to play around with home automation products. As I’ve mentioned in a previous article, it’s ok to take baby steps into home automation. I’ve been slowly adding devices in my home and started with installing outlets around my home that I can use with home kit. I’m not sure yet if any of these smart outlets will help to reduce my energy usage in a significant way, but it sure makes me feel better to know my kids are really turning off the lights.

    Over the past week I’ve installed and have been playing around with the Elgato Eve wireless weather sensors. Both units measure temperature and humidity. The room sensor adds air quality and the outdoor sensor measures air pressure. Setting these sensors up is quick and easy. Simply download the free app from the app store, sync them to your phone by verifying a serial number and you’re ready to go!

    The Eve “**wireless weather sensor**”:http://www.smalldog.com/product/88351/elgato-eve-weather-wireless-outdoor-sensor installed quickly outside. The sensor reports the temperature, humidity and air pressure with what I would consider fairly high accuracy. I did initially set up the unit inside and one observation on the negative is it took quit some time to accurately report on the outside temperature. It’s also important to note that it’s only water resistant, so you’ll want to install it in a location outside where it’s out of direct contact with the elements. I set up the Eve “**room**”:http://www.smalldog.com/product/88350/elgato-eve-room-wireless-indoor-sensor in my bedroom. I have some allergies and wondered if I would notice a difference in some of my symptoms based on its air quality readings and humidity. I’ve been making a greater effort to let fresh air circulate through my room, a challenge sometimes in Vermont winters. I have noticed my breathing is better since being able to monitor the air quality closer.

    Aside from the ability to simply better monitor weather conditions via HomeKit from anywhere, the eve app itself provides you with accumulative data. I can look for example and see what my average room humidity has been over the last week specifically in my room. To see this more detailed information you do need to use the even app. HomeKit cannot provided the details maps and statistics, but the benefit of HomeKit is I can see everything at a glance.

  • Passwords, Open Sesame?

    I cannot begin to tell you how many times I have been helping a customer with a new Mac or a troublesome Mac and the customer cannot remember their password. They start rummaging through sticky notes, old postcards or well-organized notebooks. I was at a customer’s home yesterday and needed to set up her email and iCloud account. I asked for the administrator password for her Mac and she went to a little pile of sticky notes and tried to find the right one and the scene was repeated for each password we needed. I then proceeded to show her Keychain Access and I could see the light bulb hovering above her head as she understood the value of this app from Apple.

    Mac OS X supports what are known as keychains: secure storage lockers for certificates, passwords, or any small bits of information to be kept private. The primary purpose of a keychain is to remember passwords for various applications and accounts such as mail and ftp servers, web sites, or encrypted disk images. The basic idea is that a single password, the keychain password, is used to unlock access to all passwords stored in that keychain.

    I keep Keychain Access in my dock and use it all the time to find passwords, banking information, or secure notes. To find Keychain Access you follow this path: Finder > Applications > Utilities > Keychain Access. I do recommend that once you find it that you drag it to your dock, because once you start using it, you will wonder how you ever lived without it.

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    With the advent of iCloud and OS X 10.9 Mavericks, Apple made Keychain even more valuable as iCloud Keychain lets you share your Keychain in the iCloud so you can access it from all of your devices. I wish there was an app like Keychain Access on your iOS devices but still, it is awful handy to have your device automatically remember your password for websites, etc.

    When you launch Keychain Access you will see that the window is divided into three panes. The top-left pane lists keychains accessible to you. Below this is the Category pane. Here you can choose to view specific kinds of things stored in the keychain: passwords, secure notes, certificates associated with your account, encryption keys, and certificates used by your Mac. The largest pane, to the right, displays the contents of selected category items–for example, all of the items that have a password associated with them. Except in the case of certificates, you can double-click on one of these items to open a window where you can view the item’s attributes: name, kind, associated account, location (a website or network address), as well as its access control.

    Keychain Access can do a lot of useful things. For example, if you’ve forgotten a password and would like to recover it, Keychain Access is the place to go. To learn the identity of a password, select All Items or Passwords in the Category pane, then find the the item you want the password for and double-click it. In the resulting window, enable the Show Password option. You will be prompted for the password for the login keychain which is either your login password or the administrator password (which will be the same if you are an admin user on your machine). Enter that and click Allow, and the password will be revealed in the Password field.

    I have just scratched the surface of this great utility, perhaps we will go into some more technical detail in our sister eNewsletter, Tech Tails or in a future issue of Kibbles & Bytes. But if you are not using Keychain to its full potential, I suggest dragging it to your dock and checking it out!