Archive

Posts Tagged ‘power’

MT87 Digital Clamp Multimeter Hands On

October 11th, 2014 5 comments

When you want to measure power/current on electrical device, a kill-a-watt is the easiest method, but it’s not always possible for items like air conditioner, water pumps, etc… because they may simply be no plug to disconnect. Luckily, current clamps are made just for this purpose, where you simply place one of the two wires in a clamp / loop, and it magically measures the current.  You can’t put both wires inside the loop or measurement will not work at all. The good news is that such devices are very inexpensive, and I bought MT87 digital clamp multimeter, which is also a multimeter adding voltage and resistance measurement capability, for just $11.33 on DealExtreme.

MT87_Digital_Clamp_MultimeterMT87 comes with measurement leads (voltage/resistance only), and a user’s manual. The linked user’s manual is not exactly the same document, but very similar, and also refers to MT87C model which adds temperature measurement.

There are three ranges for alternative current (20A, 200A and 400A), 600V ranges for alternative and continuous voltages, a 200 kOhm range with 100k resolution, and a diode and continuity option with buzzer. So it’s pretty much for heavy duty measurements, and not useful for low power devices, but it’s not what it’s for. The button of the right on the device is used to hold data, so if it’s in location you can’t read the display during measurement, you can press the button, take out the clamp and read the measurement.

I haven’t tried the voltage and resistance measurement. After inserting two AAA battery in the device, the first challenge was to find an electric appliance with the two cables already separated, since I did not want to use a cutter on the power cords of my appliances. First I found I could do that with my water pump, measuring around 2A @ 230V, so 460W. But them I realize the cables from the street to my house were easily accessible, and properly insulated, so I should be able to measure the full power consumption of my house, but simply clamping the device to one of the cables.

MT_87_House_power_consumptionAnd I did get measurements which are consistent with the results I got for my computer and fridge using my now defunct kill-a-watt clone:

  • Computer only – 0.74 to 0.80 A (~ 180 Watts)
  • Computer + fridge – 1.18 A (~ 270 Watts)
  • Computer + 9,500 BTU aircon – 3.99 A (~ 920 Watts)

So based on these few results, it works nicely, and it can be a useful and affordable tool to evaluate how much power your household appliances consume.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Hardware, Testing Tags: power, review

DIY Power Measurement Board

July 23rd, 2014 6 comments

When I review media player or development boards, I’m often asked about power consumption figures. One way to measure power consumption is to use a Kill-a-Watt, but for low power devices it’s not always accurate enough, and it also includes the heat dissipation from the power adapter, which may or may not be useful depending on what you want to measure. For USB powered devices or boards, an easy way to measure power consumption is to use CHARGER Doctor, a small $5 USB dongle that displays both voltage and current alternatively. Unfortunately, most products I’ve received lately use barrel type connectors, so this little tool has not been as useful as I hoped. The only solution is then to measure voltage and current with a multimeter. Voltage is measured in parallel, so you just need to point the multimeter’s leads where you want to perform the measurements. However, the current is measure in series, so you need to insert the multimeter in the circuit somehow. A few possibilities:

  1. Unsoldering a component on the board to place the multimeter in series.
  2. Cut one wire of the power cable to insert the multimeter.
  3. Get and make a board to insert the multimeter.

Solutions 1 and 2 are not really desirable, so I decided to look into solution 1, and since I could not find any board that could match my requirements, I decided to work out a solution by myself allowing various power inputs and outputs.

Click to Enlarge

Click to Enlarge

The board can take power adapter using micro USB, mini USB or 5.5/2.1mm barrel connectors, 32 different output connectors thanks to two cables, and header pins are used to connect the multimeter’s leads.

Here’s the different components required for this solution:

  • 1x perfboard or veroboard
  • Some 2.54mm pin headers (straight and right angle)
  • micro USB breakout board – $1.50 on Adafruit, but shipping + insurance was $12, so instead I purchased 5x micro USB charging board for $4.24 on Ebay (asp_ezone)
  • mini USB breakout board – $1.95 on Sparkfun, but shipping killed it again, so I purchase 2x mini USB charging boards for $2.75 on asp_ezone shop.
  • 5.5/2.1mm DC power socket –  $4.18 for 10 pieces
  • USB Female DIP Socket Connector – $1.73 for 10 pieces
  • 6-in-1 Universal USB charging cable – $3.41
  • Universal 28-in-1 DC power socket / plug converter for laptop – $11.30

If you purchase everything from scratch the cost would be around $35.

In case the introduction is not clear, the board description below may help.

Power_Measurement_Board_Description

Iv’e also included the back of the board with the soldering for reference.

Power_Measurement_Board_BackAfter double checking I had made mistake inverting GND and VCC, which could be fatal, I tried it out by making some power measurements with Tronsmart Vega S89 Elite.

Tronsmart_Vega_S89_Elite_Power_Off_Power_ConsumptionIn power off mode, I get 115 mA (~ 575 mW @ 5V), so I’m confident it’s working just fine… Unfortunately, I quickly realized something is wrong as the boot does not complete most of the time, as it reaches 1A, the boot just simply stops, or I just get a blue screen. Only once or twice did I managed to get to the home screen (about 0.52A after most background tasks are done), but starting an app will hang the system most of the time. So  I’ve tried to replace the multimeter by a breadboard female to female cable, and everything works normally. So I suspect the contact surface with the leads is not large enough, or the multimeter introduces some noise that disturbs the device…. I’ll get some crocodile clips to see if things work out better…

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Hardware Tags: how-to, power, tutorial

iFans EL-PB-17 is a 3-in-1 USB Wall Charger with a Battery and an SD Card Slot

May 27th, 2014 2 comments

I’ve noticed TYLT ENERGY 2K a USB wall charger with an internal 2,300 mAh battery, is currently on Kickstarter for $20, and received some press coverage. The main advantages of this system is that it saves space ,and you don’t need to remember charging your phone and your USB power bank separately, it will just charge both within 3 to 4 hours. However, since I’ve recently purchased a USB solar power bank with a 30,000 mAh battery (actual 8,000 to 10,000 mAh) for about $25, I thought there must be better options with a larger batter and similar price, or cheaper price with a similar battery size. It turns out there aren’t so many options, but I did find NewTrent Travelpak Plus with a 7,000 mAH battery that sells for about $40 on Amazon and even $19 on Ebay. But I’ve found a product even more original and versatile with E-link Technology’s iFans EL-PB-17 that can either be a simple USB wall charger, a standalone 3,000 mAh power bank, a USB wall charger with internal battery, or an SD card reader.

ifans_usb_wall_charger_with_batteryJust like TYLT charger it has a US-type foldable plug, but you can also use the power bank directly, if you wish to charge it from your PC or laptop for example. If you combine the AC adapter with the 3,000 mAh, you can charge your phone / tablet and power bank in one go, and it’s small enough to carry easily.

Here are the specifications listed on the company website:

  • Battery
    • Capacity – Lithium Ion 3,000 mAh
    • Input – DC 5V – 800 mAh
    • Battery Output – DC 5V – 1A
    • Misc – Power button, battery life indicators
  • USB Wall Charger
    • Input – AC 100~240 V ~50/60Hz, 0.15 A
    • Output – DC 5V – 1A

If you’re thinking it could do a neat ARM board / device UPS, it may not work as expected because there might be a delay while switching between AC power to battery (TBC). At least, this is the way TYLT charger works.

I could not find this exact model for sale anywhere yet, but the 2-in-1 model (also called EL-PB-17?), without an SD card reader, for $29.99 on Amazon or $36.99 on Aliexpress.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Hardware Tags: power, usb

USB Solar Power Bank Review

February 21st, 2014 10 comments

A few months ago, I won a $5 coupon for DealExtreme, and decided to buy a “Portable 5V (30,000mAh) Li-ion Battery Solar Power Bank w/ Dual USB + LED – Black + White” for just over $20. For the price, solar charging was a nice bonus, and the 30,000 mAh was probably a “mistake” but it did not really matter. The SKU is gone, but 1BA-2 Solar power bank ($23.97) appears to be a very similar product. I did not plan to write about this gadget, but a few things happened that made me change my mind.

First. it took over two months to reach me, instead of the usual 2 to 4 weeks. I ordered on the 9th of November 2013, and received the package on the 25th of January 2014. The reason being that the package got declined by Thai immigration (I live in Thailand). DealExtreme could not explain me why, but I assume it could be because of stricter regulations regarding batteries. They then sent the power bank via Sweden Post which usually takes an awful lot of time, as it goes to Sweden first, before coming back to Asia.

But let’s check the device itself which I received in the parcel below.

Solar_USB_Power_Bank
You’ll find the power bank, a USB cable, adapters (mini USB, micro USB, and proprietary crap for Samsung, Nokia, and Apple devices), a user’s manual entirely in Chinese mentioning the model is XHL-2000 or XHL-3000, and a pouch.

Solar_USB_power_Bank_Accesories
On the power bank, you’ll get 2 USB output (1A and 2A), a power button to start charging, or lit up the white LED (long press), a micro USB port to charge with a power adapter, and 4 blue LEDs to indicate charging status and current charge level.

Click to Enlarge

It came with a charge and I could charge my phone a couple of times. Then I decided to charge it outside, placing it on a location with good sun exposure (a roof) to see how fast it would charge, and after 6 days, the charge level showed 2 LEDs on (26% to 50% charge).

Chiang_Mai_Winter_Weather_SunIt’s winter here, so it might charge faster when temperature and day length rises. It got about 7 hours direct daily sun exposure. The weather during the test is shown on the right. The power bank will also charge when it’s cloudy or there are shadows, albeit probably at a slower rate.

I could charge my phone (1800 mAh battery) twice after 6 days of charge. That means a full charge would typically take between 10 and 20 days depending on conditions, and that you can’t expect to charge your phone daily with this device.

I should have known this at the time of purchase based on the specifications:

  • Solar Panel – 1.5W
  • Capacity – 30,000 mAh/111wh
  • Input – 5V/1A
  • Output – 5V/1A and 5V/2.1A
  • Dimensions – 120x75x26mm
  • Weight – 350g
  • Temperature range – -20 to 65 C

Under ideal & theoretical conditions charging at 1.5W for 10 hours day would take over 7 days to fully charge the power bank.

If instead of charging with solar power, I use a standard 5V/2A power adapter, the power bank can be fully charged within 9h30. I can then charge my phone about four times, which means the actual capacity is closer to 8,000 or 10,000 mAh instead of the 30,000 mAh advertised. Charging my phone from the power bank takes about 2h10 from the 5V/2A output (15% to 100%), and 2h55 from the 5V/1A (9% to 100%), which is only slightly longer than using directly a power adapter.

I’ve also tried to open this gadget, but failed to completely dissemble it.. I could however see it’s based on four 3.7V Lithium-ion batteries as found in mobile phones without being able to read the capacity. You may also want to remove the plastic protection for better efficiency.

Solar_Panel_Power_Bank

In any case, I got taught a few lessons, some of which I already knew:

  • Purchasing batteries overseas may be a problem with customs due to new regulations.
  • Specifications can be wrong or misleading (no kidding)
  • Some people sell products with virtually useless features (with regards to solar charging)
  • Sweden post can be terribly slow

I’ll still use this power bank, especially when traveling, but I’ll keep charging my phone the old-fashioned way, i.e. with a power adapter, for now.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Hardware Tags: power, review, smartphone, solar, usb

Linux Kernel 3.13 Release

January 20th, 2014 3 comments

Linus Torvalds announced the release of Linux Kernel 3.13 yesterday:

The release got delayed by a week due to travels, but I suspect that’s just as well. We had a few fixes come in, and while it wasn’t a lot, I think we’re better off for it. At least I hope so – I’ll be very disappointed if any of them cause more problems than they fix..

Anyway, the patch from rc8 is fairly small, with mainly some small arch updates (arm, mips, powerpc, s390, sparc, x86 all had some minor changes, some of them due to a networking fix for the bpf jit). And drivers (mainly gpu and networking). And some generic networking fixes. The appended shortlog gives more details.

Anyway, with this, the merge window for 3.14 is obviously open.

Kernel 3.12 brought new features to BTRFS and XFS file systems, PC’s GPU drivers improvements, better memory handling, and more. The key changes made in Linux 3.13 are as follows:

  • Scalable block layer for high performance SSD storage – This release includes a new design for the Linux block layer, based on two levels of queues: one level of per-CPU queues for submitting IO, which then funnel down into a second level of hardware submission queues. The mapping between submission queues and hardware queues might be 1:1 or N:M, depending on hardware support and configuration. Experiments shown that this design can achieve many millions of IOs per second, leveraging the new capabilities of NVM-Express or high-end PCI-E devices and multicore CPUs, while still providing the common interface and convenience features of the block layer. Read Linux Block IO: Introducing Multi-queue SSD Access on Multi-core Systems for details.
  • nftables, the successor of iptables – nftables is a new packet filtering framework that solves iptables problems and limitations, while providing backwards compatibility for current iptable users. A new user-space tool called nftables, and a new library (libnftables) are available. How-to of the new utility and syntax is available here. Video talk about nftables: http://youtu.be/P58CCi5Hhl4 (slides). Project page and utility source code: http://netfilter.org/projects/nftables/
  • Radeon: power management enabled by default, automatic GPU switching, R9 290X Hawaii support
  • Power capping framework – This release includes a framework that allow to set power consumption limits to devices that support it. It has been designed around the Intel RAPL (Running Average Power Limit) mechanism available in the latest Intel processors (Sandy Bridge and later, many devices will also be added RAPL support in the future). Documentation can be found here.
  • Support for the Intel Many Integrated Core Architecture – This release adds support for the Intel Many Integrated Core Architecture or MIC. Tianhe-2 at the National Supercomputing Center in Guangzhou, China, utilizes this architecture to achieve 33.86 PetaFLOPS.
  • Improved performance in NUMA systems – Modern multiprocessors (for example, x86) usually have non-uniform memory access (NUMA) memory designs. Linux 3.8 included a new NUMA foundation that would allow to build smarter NUMA policies in future releases, many of which are implemented in 3.13. Artcile: NUMA scheduling progress
  • Improved page table access scalability in hugepage workloads – The Linux kernels tracks information about each memory page in a data structure called page table. In workloads that use hugepages, the lock used to protect some parts of the table has become a lock contention. This release uses finer grained locking for these parts, improving the page table access scalability in threaded hugepage workloads.
  • Squashfs performance improvement – Squashfs, the read-only filesystem used by most live distributions, installers, and some embedded Linux distributions, has got important improvements that dramatically increase performance in workloads with multiple parallel reads. One of them is the direct decompression of data into the Linux page cache, which avoids a copy of the data and eliminates the single lock used to protect the intermediate buffer. The other one is multithreaded decompression.
  • TCP Fast Open enabled by default – TCP Fast Open is an optimization to the process of stablishing a TCP connection that allows the elimination of one round time trip from certain kinds of TCP conversation, which can improve the load speed of web pages. It was added in Linux 3.6, improved in  Linux 3.7, and Linux 3.13 enables TCP Fast Open by default.
  • NFC payments support –  This release implements support for the Secure Element. A netlink API is available to enable, disable and discover NFC attached (embedded or UICC ones) secure elements. With some userspace help, this allows to support NFC payments, used to implement financial transactions. Only the pn544 driver currently supports this API.
  • Support for the High-availability Seamless Redundancy protocol –  High-availability Seamless Redundancy (HSR) is a redundancy protocol for Ethernet. It provides instant failover redundancy for such networks. It requires a special network topology where all nodes are connected in a ring (each node having two physical network interfaces). It is suited for applications that demand high availability and very short reaction time.

Further details on Linux 3.13 are available on Kernelnewbies.org.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Linux, Linux 3.0 Tags: Linux, driver, gpu, intel, kernel, nfc, power, squashfs, ssd

$5.40 CHARGER Doctor Makes USB Power Measurements Easy

December 28th, 2013 12 comments

One way to make power measurement for USB powered devices is to make your own USB cable to allow for current measurement via a multimeter, but if you think it’s just too much hassle, I’ve found and purchased a small test device called CHARGER Doctor that shows voltage and current on a 4 digit display, and sells for $5.40 on DealExtreme.

CHARGER_Doctor_USB_Voltage_Current_TesterThe device features a USB female out port, and a USB male input port, that you can place between your USB power adapter, and the cable to your device to alternatively display voltage (4 seconds) and current (9 seconds). It can be used for power consumption measurements, to test if your charger is working normally, or finding out the power adapter that will charge your phone the fastest. It’s said to support measurement between 3.5 to 7V and 0 to 3 A, with an accuracy of +/- 1%.

I’ve shot a very short video showing the CHARGER Doctor attached to my phone charger.

Reviews on DealExtreme are mostly positive saying the device is accurate, however some people said it does not support data, whereas others don’t experience this issue. I’ve connected it between my hub and my camera, and I had no problem browsing the files. However, I would only get proper voltage readings, with current always showing as 0.00A, even when importing videos to my computer. Doing the same test with a USB thumbdrive worked apparently fine showing 5.15V and 0.08 A.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter

Categories: Hardware Tags: power, usb

MCU Energy Efficiency Benchmark – Freescale KL02, Microchip PIC24, TI MSP430, and STMicro STM32L

August 16th, 2013 4 comments

Freescale has recently uploaded a video comparison the energy efficiency of several micro-controllers: Freescale Kinetis KL02, Texas Instruments MSP430, STMicro STM32L, and  Microchip PIC24. Since it’s a Freescale video, we already know the winner, but the test they performed it still interesting, and it shows drastic performance differences between architectures.

The used the following exact MCU for testing:

Freescale did not really select tough competition such as NXP LPC800 Cortex M0+, but instead a Cortex M3 MCU, and older 16-bit MCUs. I don’t know if Microchip has a new generation of ultra low power 16-bit MCUs , but Texas Instruments, for example, launched MSP430 Wolverine MCUs at the end of last year. So this comparison may not be very interesting to find out which company has the best MCU in terms of energy efficiency, but as I mentioned above, we’ll see clear differences between architectures, and I find the setup used for testing interesting.

The hardware setup is shown below.

Freescale_STMicro_Microchip_Texas_Instruments_Testbed

We’ve got four board with the MCUs mentioned above, with 4 fully charged capacitors, and a Freescale MCU measuring the voltage in the capacitor.

MCU_Energy_Efficiency_Test_Software_Flow

Each board is loaded with software that follow the flow chart above. Each board runs Coremark, acknowledges it’s done, sleep 5 seconds and repeat. If the voltage in the capacitor is not high enough for the MCU, there won’t be acknowledgment and the test ends. This power consumption “benchmark” measures the energy efficiency under heavy load, and not the standby power that may be the most important part in some applications.

Freescale_Kinetis_Energy_Efficiency_Demo

Then they visualize the real-time capacitor voltage level, CPU power consumption for all platforms. MSP430 is the device that takes the longest time to execute Coremark, and stops after only 2 cycles, because the capacitor can not deliver the minimum voltage required by the chip (2.2V). Microchip PIC24 stops after 12 cycles (1.76V), STM32L after 20 cycles (1.77V), and KL02 continues but we don’t get to see for how long.

You can watch the 5-minutes video to see the complete test.

Digg This
Reddit This
Stumble Now!
Buzz This
Vote on DZone
Share on Facebook
Bookmark this on Delicious
Kick It on DotNetKicks.com
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter