Shower by cell phone and the attitude of gratitude

As I type this, I’m sitting on an airplane, clean, comfortable (as much as that’s possible sitting in economy), clean shaven, well fed, flying home to New Jersey from Frankfurt. Things could have been different…

I started my travels today from a hotel in Sindelfingen, Germany, drove to the Stuttgart airport, and took a short flight to Frankfurt where I connected with this much longer flight home (8.5 hours). I was visiting some of Agilent’s distribution partners in Germany and France over the last ten days to present training on our newest power supply products.

Last night, before I went to sleep, I called the front desk of the hotel to ask for a 6 am wake-up call. I wanted to have time to shower, shave, dress, eat breakfast, check out, gas-up the car, drive to the airport, return the car, exchange my leftover Euros for US dollars, and finally make my morning flight. I also set my new cell phone alarm for the same time (6 am). I recently purchased my first smart phone, so I’m happy to be using its features!

6 am rolls around, my cell phone alarm goes off (yes, I managed to set it correctly), and I wake up momentarily not knowing exactly where I am or what is happening (typical for trips where you change hotels a lot). 5 seconds after the alarm starts its intermittent beeping, I come to my senses in my nearly pitch-black, normally very quiet room. The only light is a dim glow from a tiny LED on the room thermostat and the only sound is a low hum from the heating system fan in between the alarm beeps. 10 seconds after the alarm started beeping, the room suddenly become absolutely pitch-black. No light at all! I wonder if I’m dreaming and I feel like I have completely lost my eyesight! But then I noticed that the heating system fan went from humming to silent, and the thermostat LED is no longer glowing. Totally dark and totally quiet (between phone beeps) with no thermostat LED and no fan? OK, perhaps I’m not dreaming and most likely, this is a power failure! In the absolute darkness, I fumble for my beeping cell phone and manage to push a button on it partially illuminating the screen. I turn off the alarm, and now can see just enough to try the lamp switch next to the bed. Click, click on the lamp….no light. Yeah, definitely a power failure. I know that the cell phone, an Apple 5S, has a flashlight feature that is a nice, bright white LED. Turning that on, I’m now able to easily maneuver around the room. I pick up the room phone, but it is dead. I look outside, and it is dark everywhere. Yep, it’s not just my room, nor is it just the hotel. The power is out everywhere. Guess I won’t be getting my 6 am wake-up call!

Next, it is time to shower. I strategically place the cell phone on the bathroom counter angled just right so the light bounces off the ceiling and I can see reasonably well in the shower. Shaving is a bit more difficult with the limited and oddly angled light, but I manage. Then the lights come back on. Whoo-hoo!  About 10 minutes later, the hotel phone rings and the manager is very apologetic about the wake-up call being 40 minutes late. I tell him “no problem” and explain my phone alarm still woke me on time.

So had my cell phone alarm not awakened me, I may have slept too long resulting in a missed flight. And if I did not have the flashlight feature on the phone, I would not have been able to shower and shave making me more comfortable during a full day of travel. Earlier in my trip, the cell phone GPS also saved my colleague and me by guiding us to our hotel, to the office, and enabling us to find our way back to the hotel after walking around town for lunch.

Cell phones play a very large role in our lives today. While we humans survived the vast majority of our existence without them, smart phones and all electronic technology have vastly changed our lives. While I regularly wonder how my life would have been different had I lived in a time without electricity, today, my smart phone changed my experiences. I could have missed my flight had my cell phone alarm not gone off. I could have been less comfortable during my long travel day had I not been able to shower by cell phone light. Despite a power failure preventing a wake-up call and no light in my hotel room for the early morning, my day was not really disrupted thanks to my cell phone. While these things are minor in the grand scheme of things, I am still grateful for the technology we have that allows us to do the things we do. And I’m glad to be a part of that technology by working with power products. Many cell phone manufacturers use Agilent power products during their design, verification, and manufacturing processes and I am happy to be a part of that chain.

May all of your travels during this holiday season be uneventful…and Happy New Year!

Fun at Matt's desk!

I am about to head out for a week long vacation (actually Gary will be there too) so I wanted to do something short and fun for this month’s blog post.  I have been with Agilent 13 years come mid June (man I am getting to be old).  Through the years, I have collected some interesting items on my desk.  I wanted to share some of the more interesting items that I have collected through the years.

Item 1:

What do you think this green object is?

If you answered a 2500 Watt resistor then you’re right!  This particular resistor is rated for 0.8 Ohms. Agilent sells power supplies that are rated all the way up to 6.6 kW so sometimes you need a high power resistive load.  I personally would not put 2500 W through this resistor unless I had a whole lot of ventilation.  Luckily last time I used it I only put like 1500 W through it so it only got mildly toasty.   

Item 2:

How much voltage do you think that this probe can measure?

This is the Agilent 34136A high voltage probe for our DMMs.   Before I acquired this probe, I was used to teeny tiny normal alligator clip probes but this probe can measure up to 40 kV!.  I don’t know about any of you readers but I probably would not want to be anywhere near a 40 kV Voltage myself.  This probe  has banana plugs on it and you can hook it up to our DMM products (34401A, 34410A, etc.).  This probe almost looks like a sword of some sort with the pointy tip and all.

Item 3:

How much capacitance do you think this smallish capacitor is rated for?

This is a 10 F capacitor.  That is right 10 Farads!  When I was in college, a 10 Farad capacitor was unthinkable, now you can find them in these tiny packages.   My colleague Paul used this to research this video: http://www.youtube.com/watch?v=Flv6s94gBXE.

So this is just a quick tour of some of the neat stuff around my desk.  What kind of neat engineering stuff do you readers have on your desks?  Feel free to share in the comments.

Happy Summer everyone!

Happy New Year! May it be a “powerful” one!!

I just want to take this opportunity to thank all of our readers for taking an interest in the Watt’s Up? blog posts. Power-related topics have been a part of our professional careers (and personal lives) for decades and we are both thrilled and honored to be able to share some of what we have learned over the years with you, our readers.

During 2012, we have seen our readership grow by more than 5 times that of 2011! And we hope to see that growth continue during 2013. To make that happen, we would like to hear from you, our readers, about what power-related topics are of greatest interest to you for 2013. Please comment below and we will be happy to post about any power-related issues you bring up!  

Finally, on behalf of Ed Brorein, Matt Carolan, and myself, and all of us at Agilent Technologies, Happy New Year! May 2013 be a “powerful” year for you all!!

Battery-killing cell phone apps? – Part 2

Back on May 25, 2012, I posted about mobile device users avoiding security apps because they think the apps run down their batteries too quickly (read that post here). I also mentioned that a member of the Anti-Malware Testing Standards Organization (AMTSO) is using Agilent’s N6705B DC Power Analyzer to evaluate just how much the security apps affect battery run time and that the results would not be available for a few months. Well, the results are in and guess what? Which security app you choose does not make much difference in your battery run time.

On average, they reported that the effect of using a security app on reducing battery run time is only about 2% which translates into less than 30 minutes of lost battery life per day. And the study went on to explain that the differences in performance of one mobile security product to another were small (they tested 13 products each from a different vendor). I was amused by the author’s comment that they were “not providing a ranking” because it “could get misused by marketing departments”. Indeed!

Here is a link to the report:
http://www.av-comparatives.org/images/docs/avc_mob_201209_en.pdf

The report shows a picture of Agilent’s N6705B DC Power Analyzer as the measuring device. They used this product because “This high-precision instrument can measure battery drain exactly”. A screen shot of Agilent’s 14585A Control and Analysis Software for the DC Power Analyzer was also shown in the report. The software allowed them to evaluate power consumption while performing various mobile phone tasks, such as making phone calls, viewing pictures, browsing websites, watching YouTube (I wonder if they watched any of the DC Power Analyzer videos we have posted!), watching locally stored videos, receiving and sending mails, and opening documents.

If the N6705B DC Power Analyzer and 14585A Control and Analysis Software can evaluate power consumption for all of those things, just think of what it could do for you! Check out Ed’s post from earlier this week for some of those things: http://powersupplyblog.tm.agilent.com/2012/09/optimizing-mobile-device-battery-run.html

Test of Time power supply contest winners announced

Earlier this week, the winners of Agilent’s Test of Time power supply contest were announced. Here is a link to the press release:

http://www.agilent.com/about/newsroom/presrel/2012/25jun-em12080.html

I found the Test of Time contest to be quite interesting and I was honored to be one of the judges for the contest. The contest invited engineers who were using vintage Agilent or Hewlett-Packard (is there a “vintage” Agilent supply?) or even the older Harrison Labs power supplies (HP power supplies started as Harrison Labs power supplies) to describe their application, writing about how the instrument has been used over the years and how they are using it today. We received quite a few entries and we had extensive discussions to choose what we considered the best entry based on the contest rules. Go to this link for the home page of the contest and select the Gallery tab to see all of the entries:
http://powercontest.tm.agilent.com/

Richard Factor, of Little Ferry, NJ (I did not know he was from NJ until after I submitted my choices as a judge) won one of the prizes: an N6705B DC Power Analyzer with three modules installed. Quite a nice prize, and well deserved based on Richard’s entry!

Richard used an old HP 6186B in an application that basically turned his Toyota Prius into a backup generator for his house during a power failure. Now that’s what I call a unique application! You can read more about it at these links:

http://priups.com/agilent%20contest/hp-6186b-entry.htm

http://www.priups.com/ (you must select the correct answer….I’m sure you’ll figure it out….)

Simon Jensen of Husum, Germany, also won an N6705B for his entry. Simon’s entry was chosen by readers of the stories who voted for their favorite. Simon used an Agilent 6632B power supply as an inexpensive load to sink current from a switching power supply he built. As Simon correctly points out, the nameplate on this power supply does not reveal all of its capabilities. It says 0 to 5 A, but it can also sink a programmable, regulated current like an electronic load. So the nameplate should say -5 A to +5 A, as pointed out by Simon!

Having worked for HP/Agilent on power products for more than 32 years (since 1980), it was not too surprising for me to see so many interesting applications for our products. I was also delighted, and not too surprised, to see how many of our older power supplies are still out there, providing power, decades after they were introduced! Now that’s what I call “vintage voltage”!!

*OPC and You

Today I have a guest-blogger, one of my Agilent colleagues (and friends), Matt Carolan. Matt has experience with programming our power products, so I asked him if he had anything he wanted to share with our audience. He has many things to talk about and will most likely contribute to future posts, but decided to start with the *OPC command, which is the “Operation Complete” command. Here is Matt’s post:

Hi, my name is Matt and I am an Application Support Engineer at Agilent Technologies. I have had 12 years of experience programming our power products and I wanted to write about a small but powerful command, *OPC.

*OPC is a standard IEEE-488.2 command that allows you to synchronize your power supply with your program. *OPC lets you know when all pending operations are complete. A pending operation is something such as the voltage being set or the output turning on. I worked as a test engineer for a few years and we always used the *OPC command in our calibration routines. We would send a calibration command (such as CALibration:LEVel:P1) followed by a *OPC? query. This allowed us to ensure that the calibration command had finished executing and that the power supply should be outputting the correct level before we took any measurements with our test system.

    

There are two ways to use *OPC. There is a standard *OPC command and the *OPC? query. The *OPC command will set bit 0 of the Standard Event Status register when all pending operations are complete. You can then use a *ESR? Command to poll the Standard Event Status Register. When this returns a 1, all pending operations are complete. When you use this command, it only works for any pending commands that were sent BEFORE you sent the *OPC command. It will not work for commands sent after the *OPC command. You can send another *OPC command to start the cycle again.

The other way is to use it as a query. When you send a *OPC? query, it will put a 1 in the output buffer when all pending operations are complete. The main drawback of this method is that if there is an operation that takes a long time to complete, your *OPC? query will timeout. You would need to have a long timeout set in your IO library to avoid this. You cannot send any commands after the query without getting an error so this will hold up your program until all pending operations are complete.

If you have any questions please comment here or on the Agilent forum at: http://www.agilent.com/find/forums

Battery-killing cell phone apps?

Two days ago, I came across an article entitled “Do Android Security Apps Kill Your Batteries?” The article talks about mobile device users avoiding security apps because they think the apps run down their batteries too quickly. A member of the Anti-Malware Testing Standards Organization (AMTSO) is using Agilent’s N6705B DC Power Analyzer to evaluate just how much the security apps affect battery run time. While the results are not yet complete, the researchers are planning to measure power usage with no security app running, with the app running in the background, and with the app actively working. Their full report is due out by the end of July. Here is a link to the article, written by Neil Rubenking in his SecurityWatch blog for PC Magazine Digital Edition:

http://securitywatch.pcmag.com/mobile-security/298170-do-android-security-apps-kill-your-batteries

I was pleased to see the N6705B DC Power Analyzer used in this way – this product has power modules and software that are specifically designed to do exactly this type of evaluation!

If you have to evaluate a mobile device’s battery run time for any reason, here is a link to “10 Tips to Optimize a Mobile Device’s Battery Life” written by our own Ed Brorein (contributor extraordinaire to this blog):

http://cp.literature.agilent.com/litweb/pdf/5991-0160EN.pdf

And here is a link to Ed’s post from a few months ago on “Using Current Drain Measurements to Optimize Battery Run-time of Mobile Devices”:

http://powersupplyblog.tm.agilent.com/2012/03/using-current-drain-measurements-to.html

When the researchers complete and publish their evaluation on how security apps affect your cell phone battery run time, we’ll be sure to follow-up with another post! In the mean time, protect your phone in whatever way you like, and keep charging ahead by charging your batteries!

What Is Old is New Again: Soft-Switching and Synchronous Rectification in Vintage Automobile Radios

I have to admit I am a bit of a vintage electronics technologist.  One of many pass times includes bringing vintage vacuum tube automobile radios back to life. In working with modern DC sources I’ve seen innovations come about in the past decade for efficient power conversion, including soft switching and synchronous rectification. A funny thing however, for those who have been around long enough, or into vintage technologies like me, is that these issues and somewhat comparable solutions existed up to 70 years ago for automobile radios and other related electronic equipment. What is old is new again!

As we know, vacuum tubes (or valves to many) were to electronics back then as what semiconductors are to electronics today. The problem for portable and mobile equipment was that the vacuum tubes needed typically 100 or more volts DC to operate. They did have high voltage batteries for portable equipment but for automobiles the radio really needed to run off the 6 or 12 volts DC available from the electrical system. The solution: A DC/DC boost converter!

Up until the mid 1950’s most all automobile radios used vacuum tubes biased with high voltage generated from a rather primitive but clever DC/DC boost converter design. The inherent technological challenge was semiconductors did not yet exist to chop up the low-voltage, high-current DC to convert it to high-voltage, low-current DC. Of course if the semiconductors did exist this would all be a moot point! Making use of what was available the DC/DC boost converters employed what were called vibrators, which are a form of a continuously buzzing relay, to chop up the low-voltage DC for conversion. Maybe some of you are familiar with the soft humming sound heard when an original vintage automobile radio is turned on, prior to the vacuum tubes finally warming up and the audio taking over? That humming is the vibrator, the “heart” of the DC/DC boost converter in the radio.

Figure 1 below is an example circuit of vibrator-based DC/DC boost converter in a vintage automobile radio. This is just one of quite variety of different implementations created back then. Two pairs of contacts in the vibrator act in a push-pull fashion to convert the low-voltage DC into a low-voltage AC square wave. This in turn is converted to a high-voltage square wave by the transformer. Because the vibrator is an electro-mechanical device, it is limited in how fast it can switch. Switching frequencies are typically about 100 to 120 Hz. The transformers used are naturally the steel-laminated affairs similar in nature to the transformers used to convert household line voltage in home appliances. Very possibly some radio manufacturers used off- the-shelf appliance transformers in reverse to step up the voltage!  Often a small rectifier vacuum tube, such as a 6X4 (relatively modern, by vacuum tube standards) would be used to convert the high voltage AC to high voltage DC, but in this particular example I am showing here another two pairs of contacts on the secondary side switch simultaneously with the first pairs of contacts to rectify the high voltage AC. Highly efficient synchronous rectification, up to 70 years ago!

Figure 1: Representative DC/DC boost converter for a vintage automobile radio

Hurricane Irene and inverters

During the weekend of August 27-28, 2011, hurricane Irene wreaked havoc along the east coast of the United States. I live in northern New Jersey where we got more than 10 inches of rain in a short time! Flooding, downed trees, and power outages were rampant! My mother called me during the storm to tell me her basement was flooded. She still lives in the house where I grew up, and I know that basement had not flooded in decades. But she lost power disabling her sump pump, so the heavy rain resulted in several inches of water in the basement saturating the carpet and ruining furniture and other personal items. What a mess! And my brother, who lives in another NJ town, has a restaurant that ended up with 4 feet of water in it!! Fresh fish, anyone?

So when my mother called me for help, I gathered up various tools, buckets, hoses, extension cords, flashlights, my wet/dry vac, and stopped at a friend’s house to borrow an inverter he used when camping (thanks, Andy!). An inverter takes DC in and puts out AC. My hope was to power the inverter from my car battery and plug in my mom’s sump pump to empty out the water in her basement. Luckily, as I was driving to her house with my friend who was coming to help (thanks, Nyla!), my mom called my cell phone to let me know the power was back on, so the sump pump kicked in and pumped out the bulk of the water. Of course, a soggy mess was left behind (7 hours of wet vacuuming made only a small dent in the cleanup, but it was a start). So, it turns out I did not use the inverter at her house (it would not have provided enough power anyway), but when I went to work the next week, I figured I’d play around with it in our lab area. Here are some of the things I found…

This inverter is a Coleman Powermate (model PMP400) 400 W inverter. It takes 12 V DC in and has a 40 A fuse on the input side, and two outlets with an on/off switch on the output side.


The output is a modified sine wave (looks more like a modified square wave to me, but OK, I’ll call it by its rightful name), at nominally 120 Vrms and 60 Hz, which are the standard AC mains voltage and frequency in the US. The waveform below was captured with a scope (an Agilent MSO7054A) and shows the actual output of the inverter with 12V DC in (from an Agilent N6754A installed in an N6705A) and a light load (~32 W) on the output.



Below is what the standard AC line looks like in the US, so you can see that the inverter's output (shown above) is only an approximation of the waveshape, although the inverter does maintain the correct rms voltage and frequency:


As a load on the inverter, I powered up another one of our DC power supplies (an Agilent 66332A) by plugging it into the inverter output. I could then program the output of the 66332A power supply to a voltage (20 V), connect it to one of our DC electronic loads (an Agilent 6063B) and vary the load current (up to nearly 5 A), thereby changing the loading on the 66332A, which in turn, changed the load on the inverter.


The inverter output frequency remained very close to 60 Hz for all loading conditions, and the output voltage dropped slightly (just a few volts) as I increased the loading on the inverter. The maximum power I drew from the inverter was limited by my input power source, the N6754A, which is a 300 W, 60 V, 20 A power supply. Since I was using it at 12 V, I set the current limit on it to the maximum of 20 A providing a maximum of about 240 W to the inverter input. So I was able to exercise the inverter up to only a little over one half of its 400 W capability.

The 66332A power supply I used as my load for the inverter has a standard AC input and seemed to operate just fine when powered by the modified sine wave coming from the inverter output. Regarding other loads you might plug into the output of an inverter, I think most AC motors would operate when supplied by a modified sine wave, however other devices such as audio equipment, fluorescent lighting, and some laser printers might not work properly or at all. Inverters are available with pure sine wave outputs to more closely mimic the power supplied by your utility company, however, these tend to be much more costly – sometimes several times the cost of an equally powered modified sine wave inverter.

I looked up a few numbers about waveforms and found that a pure square wave has a THD of about 45% while a modified sine wave has a THD of about 24%. Here is an interesting article on this topic:
http://powerelectronics.com/mag/608PET21.pdf

So if you ever lose AC mains power and need to run one or more AC powered devices, you could temporarily use an inverter powered from your car battery. Just be sure to get an inverter with enough power to handle the load you will put on it, and make sure the type of inverter you choose (modified or pure sine wave output) is appropriate for the load you want to power. Although it turned out I did not need it for my mom’s sump pump, the 400 W inverter I borrowed would not have been powerful enough for the pump. The current rating on the pump was about 6 A, so at 120 V, that is 720 VA (120 V x 6 A) which is more than the 400 W inverter could provide. But how do you compare VA (volt-amperes) to W (watts), you ask? The power that a device consumes expressed in W will always be less than or equal to the power in VA, but I’ll leave that discussion for another post! For now, if you think you’ll need an inverter, get one with a W rating higher than the total VA you require. This approach may be a bit overkill, but you will definitely have enough power.