Kibbles & Bytes Blog

It’s back to usual this week for my article, because I thought of a good topic. I’ve talked many times about AC power and how and why we use it, but many things don’t use AC power. In fact, they can’t. These are things we use every single day. Virtually all digital electronics cannot use AC power directly. It needs to be converted into DC power. Remember that AC means the current is alternating and DC means the current is flowing in one constant direction.

Any time you convert electricity from one type to another, or one voltage to another, there will be losses. Nothing is free. Every time you change something about electricity, you have to pay a tax. The goal in electronics design is to minimize those losses. AC to DC conversion is one of the simplest and most efficient conversions we do on a regular basis. DC to AC conversion is also possible (accomplished by inverters). Most of these processes are on the order of 95% efficient or greater. So how do we convert AC to DC?

First off, the process of converting AC to DC is called ??rectifying??. Devices that accomplish this task are often called rectifiers. A very common rectifier design is called a bridge rectifier. To understand how they work, we have to recall that AC is a wave. Sometimes it’s voltage value will be positive, other times it will be negative. This doesn’t work for DC since the voltage has to always be positive or always be negative. Rectifiers take the negative voltage swing of the wave and flip it up top so that it’s positive. Now instead of a sine waveform, the output of the circuit will look like mountains. The voltage will always be positive, but it will still vary considerably, from the peak (approximately 170 volts on grid-level 120VAC) to zero and then back up again.

How is the voltage rectified? In a bridge rectifier a ring of diodes is used. Recall that a diode only allows current to flow through it in one direction. By arranging the diodes in a ring we can create a “draw off” point for the current where the voltage will always be positive. Instead of being allowed to “pull” the current backwards during the negative voltage swing, the diodes redirect it back to the output point. Of course, this only means that the negative voltages get flipped up, creating the mountain-like waveform I mentioned earlier. This is not good for DC power, so how do we fix it?

There are many ways to minimize this issue, but it can’t be fixed perfectly. One way is to use capacitors to buffer the output voltage. Instead of sinking when the mountains go back down to zero, the capacitors prop the voltage up during that period, until the next mountain peak arrives. Depending on the load, this could mean large capacitors to hold the load long enough. Remember also though that AC has a frequency on the order of 50-60Hz. This means there will be around 120 of those mountain peaks every single second, so the capacitors don’t need to hold for too long.

The other issue we have to contend with is how to reduce the voltage from anywhere between 120-240VAC to something DC electronics might expect, like 5VDC. For AC to anything, this is actually very easy; we use transformers. A transformer has two sets of wire windings, a primary winding and a secondary winding. The primary winding contains the input current, usually fluctuating AC. This fluctuating current induces a magnetic field that also fluctuates in a metal core that extends from the primary winding to the secondary winding. The changing magnetic field in the core induces a new current in the secondary winding. The induced current will necessarily be greater than the input current if the windings are configured to reduce voltage. The overall power has to remain the same. So if the input were 120VAC at 1 amp (120 watts), and the transformer was reducing the voltage by a factor of two, the output would be 60VAC at 2 amps (still 120 watts). The output of a transformer will still be AC, but this is where we would apply rectification.

This method of power conversion is extremely efficient, but as transformers are highly inductive, power companies would hate it if every single device used one. The reason for this is because inductive loads shift power around a lot without actually consuming that much. So the power company has to pay to send the power all the way from their generating station, to you, only to have your device reject almost all of the actual energy in that power. Most homes don’t have solely inductive loads though, so most of the time it’s not an issue. However, certain industrial processes rely heavily on inductive load machinery. In these cases, the power company may request that they burn off a certain amount of power in dump loads (basically huge resistors) in order to keep the grid functioning normally.

So there you have it. How we take that high voltage raw AC power from the wall and tame it to safely power all of your devices.

I have written many times on the benefits of AppleCare and how it differs from those “extended warranties” that everyone tries to sell you. Back in June, Apple converted to AppleCare+ and now adding AppleCare+ is truly the smart move.

AppleCare+ was already out there for iPads, Watch and other Apple gear but June brought this feature to the Mac. We used to be measured by Apple on our AppleCare attach rate but now that is almost a moot point since most customers do opt for the new Applecare+.

All of the features of the original AppleCare were brought over to AppleCare+. Your hardware warranty is extended from 1 to 3 years and your toll-free technical support from Apple is extended from 90 days to 3 years as well. This comes in pretty handy when your college student is cramming for an exam and needs tech support NOW. Without AppleCare+ the first thing your student would provide is a credit card number. With AppleCare+ for 3-years they can call Apple and get help.

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So, what is new about AppleCare+? Well, it is that “+” sign. AppleCare+ now covers accidental damage which is the most common problem we see when we are checking in Macs for repair. You will have to pay $99 for screen or external enclosure damage or $299 for other damage, however, if you spill that soda on your Mac you are looking at a logic board replacement at well over $500 if you do not have AppleCare+.

Let’s review each of the benefits of AppleCare+ for your Mac.

*Late Night Tech Support*
Okay, it might not always be late night but Apple is there to answer your questions 24/7 via chat or phone. Not for 90 days but for 3 years if you have AppleCare+

*Apple Hardware Coverage*
Your Mac is covered literally anywhere in the world for 3-years for both parts and labor. You can, in many cases for desktop Macs, request on-site service. For laptops you can mail them in or take it in to Small Dog Electronics or any Authorized Apple Service Provider. Or an Apple store if you must. This coverage extends not only to your Mac but also to:

* Battery
* Included accessories like the power charger
* RAM
* Airport base stations (if purchased within 2 years of your Mac purchase or while AppleCare+ is valid
* Apple USB Superdrive (who uses those anymore? I have one on my shelf)

*Software Support*
Is it a software or a hardware problem? This is a common dilemma. But since Apple makes the OS, many Apps and the Mac, too, your AppleCare+ covers the MacOS, iCloud and quick how-to questions on Apple Apps such as Photos, Pages, iMovie, etc. Don’t expect a long lesson but if you are running into a roadblock on using Keynote, for example, you can call up and get some advice. Connecting to your network and printers is also covered.

There is one important difference in buying AppleCare+ now. In the past, you had up to 1-year to buy AppleCare. We would send out reminder letters and many people did wait. But now, you have only 60-days to make that choice. Most people buy AppleCare+ with their Mac purchase because it becomes a bit of a hassle to buy it after the fact. You would either need to bring the Mac into Small Dog for inspection or set up a remote diagnostic with Apple.

Pretty much anything that goes wrong with your Mac is going to cost you more than AppleCare+ if you are not covered so that is what makes it so valuable. With all the liquid damage we have seen, I am so happy to have a better option for customers. Too many times we have had customers come in with liquid damage and be shocked at the cost to repair. Now, that wine spill will be capped at $299 with AppleCare+. I can have a different discussion now with customers when we show them that the moisture sensors have been tripped and there is the gooey sticky substance on their logic board despite their insistence that they did not spill.

The only thing that would make AppleCare+ better is if Apple would just include it with every Mac rather than asking you to buy. It is that essential to the Mac!

_Dear Friends,_

It is blueberry season and the bushes on my place on Prickly Mountain are loaded with the juicy berries. Blueberries for breakfast, blueberry pancakes and blueberry pie seem to be July’s harvest at least at my place.

I got out on my Indian and rode down to Brattleboro to meet my sister for lunch which was great. Monday I head out on the annual “Road Pitch”:https://www.roadpitch.co. This is an event where several entrepreneurs and investors who happen to also ride motorcycles go from town to town in Vermont to listen to business pitches. It is fun to hear the pitches for some very good and some not so good ideas but it also great to ride with some interesting people including the Governor of Vermont.

I need to speak out against the President’s recent misguided ban on transgender people serving in the military. We are indebted to every single soldier regardless of their gender. We need to honor all that sacrifice and serve. When we discriminate against one group of people we lessen our humanity. #LetThemServe

This week we also bid farewell to some important Apple products. We have just received word that the only iPod to survive today’s cuts will be the 32GB and 128GB iPod touch. So, goodbye to the iPod nano and shuffle, two great products!

This week’s Kibbles & Bytes exclusive features a configure to order MacBook. We have 5 or 6 of the specially built CTO MacBooks in stock. They feature the 1.3 GHz processor, 8GB of RAM and the upgraded 512GB SSD storage. These are brand new units and I have some of each color, Space Gray, Gold, Silver or Rose Gold. This week exclusively for Kibbles & Bytes readers I am “**bundling them with AppleCare+ which is just a ‘no-brainer’ and the IO Gear Ultra Slim Dual Display USB-C hub with 10 ports**”:http://www.smalldog.com/wag900002763/. I have used this hub and it is ideal for making your USB-C laptop into a great desktop. It has all the ports you need including power pass-through, ethernet and display support. This bundle would normally cost you $2030 but this week for “**Kibbles & Bytes readers it can be yours for only $1879**”:http://www.smalldog.com/wag900002763/ while supplies last.