Hardware

Ultra-budget gaming PC

http://www.maximumpc.com/build-it-little-pc-on-the-prairie/

Mini ATX

• ASRock H97M-ITX/ac

Intel CPU

• • Atom: Bay trail, Cherry trail, ...
  • Haswell
  • Broadwell
  • Skylake (sixth-generation Core series of processors) and review
  • http://www.fanlesstech.com/

My own collection

Device	Family	Instruction	Clock & Memory
Pogoplug	ARM9	ARMv5	1.2GHz, 256MB
Raspberry Pi	ARM11	ARMv6	700MHz, 512MB
Beaglebone Black	Cortex A8	ARMv7	1GHz, 512MB
UDOO	Cortex A9	ARMv7	1GHz, 1GB

See wikipedia for a list of ARM cores. These SoC are 32-bit. The newest ARM architecture is ARMv8 which is 64-bit; see here.

Arduino Yun vs BBB vs Intel Galileo vs Raspberry Pi

from Adafruit. It includes spec comparison, performance test, power usage, ...

• Arduino motor spin
• Arduino Uno vs Beaglebone vs Raspberry Pi from Makezine.com.
• Arduino Uno vs Raspberry Pi vs Beaglebone black from lifehacker.com.

Samsung pico DLP projector sp-h03

LED, 30 ANSI lumen 854x480, 12V & 1A power. The manual is available at Samsung web site here. The input signal in D-Sub can be 1280x800, 1280x768, 1280x720 resolution although the manual also said "All resolutions higher or lower than 854 x 480 are converted to 854 x 480 by the scaler chip in the projector. To obtain an optimal picture, the resolution from the PC should be similar to the projector (854 x 480)".

Vivitek Qumi Q5 500

Lumen WXGA HD 720p 3D-Ready Pocket DLP (buydig.com, vivitekusa.com)

USB device speed comparison

See http://www.elinux.org/RPi_SD_cards#Performance for an objective way to get write/read speed by using command line tool 'dd'.

Device	Read	Write	FS
MicroCenter4G	Example	12.77MB/s	Ext3
MicroCenter4G	Example	5MB/s	vfat
Patriot XT 32G USB3.0	Example	50MB/s	vfat
Patriot XT 32G USB3.0	Example	115MB/s	fat16
Patriot XT 32G USB3.0	Example	113MB/s	fat32
Patriot XT 32G USB3.0	Example	24MB/s	ntfs
Patriot XT 32G USB3.0	Example	139MB/s	ext2
Patriot XT 32G USB3.0	Example	50~100MB/s	ext3
Patriot XT 32G USB3.0	Example	140MB/s	ext4
Example	Example	Example	vfat

When testing Patriot XT USB 3.0 drive, I partition it into ext2 (15GB)& ext3(15GB). The problem of unstability in Patriot XT's ext3 partition is not related to ext3 partition because if I switch the order of partitions of ext2 and ext3, then ext2 becomes unstable.

• A word about USB flash drive.
  • According to the Slo Bytes USB Flash Drives report from Brian K. Lewis, flash drives are capable of handling 10 thousand to 10 million write and erase operations during their lifetime, depending on the source as well as the specific USB drive. Regardless, a flash drive typically will outlast any standard hard drive. The main concerns about the life expectancy of a flash drive are damage from neglect and becoming lost or stolen.
  • The life expectancy of a USB Flash Drive can be measured by the number of write or erase cycles. USB flash drives can withstand between 10,000 to 100,000 write/erase cycles, depending on the memory technology used. When the limit is reached, some portion of the memory may not function properly, leading to lost of data and corruption.
  • Most experts would agree that around 10 years is about what you can expect to retain data on a flash drive without powering it up. That means you can lock away a USB drive for 10 years and return to still see your data. After 10 years of not being powered on, the electrical charges determining if bit of information is either a ‘1’ or a ‘0’ gets hazy. This is because like all electrically charged devices, they suffer from what is called electro/magnetic deterioration; or simply put, where devices will eventually lose their power.

• The copy-paste speed on my 7200rpm hard disk is about 160MB/s.
• Tested using Seagate portable drive SRD0SP0 500GB with USM((Universal Storage Module)/USB 3.0. When it is connected to USB 2.0/3.0, the writing (from an internal hd onto it) speed is at best 30MB/s. When it is connected to USB 3.0, the writing (from it to an internal hd) speed is at least 60MB/s.
• DIY USB on the go cables.

ATX 24pin power supply

and this. A simple test from wikihow.com.

How to silence your computer mouse

An easy way to take off the cape of the rectangle box is to use a pairs of long nose pliers instead of a knife. The method works on my Logitech M210 mouse. The trick is to shorten the click distance.

Cellular phone frequency list

North America & Worldwide. In particular, T-mobile uses 1700 (3G UMTS), 1900 (3.5G HSPA+), 2/4/12 (4G LTE) and Chunghwa telecom uses 2100 for 3G/3.5G.

Lenovo IdeaTab Lynx K3011

Intel® Atom™ Z2760, 2G ram, 64GB storage.

HP Stream 8

Intel® Atom™ Z3735G Quad Core (64-bit), 1G ram, 32GB storage. The C: drive shows the space is 23.5 GB. The free space is 20GB. After the first Windows update the storage space is reduced from 18.6 to 16.8. After running Disk cleanup utility, the storage now becomes 17.1 (still lose a lot). So the lesson is not to run Windows update if the disk space is very limited (eg tablet) & everything is working fine now.

ZenFone 2

from ASUS.

Vehicle camera recorder

1. night vision 2. can turn on/off manually 3. pictures stable (not flicker) 4. G-sensor 5. 3D turning on mount racket 6. no surprising things like auto turned off, (power, start) buttons not working, freeze 7. video space (640x480 takes 100MB for 1 min???). The Amazon website has a list of popular dash cams.

Amazon Fire TV

• Navigation with the remote.
• Install XBMC/Kodi

Kill A Watt P3

Note: click the 3rd button to switch between Watt and VA; similarly for the 4th and 5th button.

Volt --- Amp --- Watt/VA --- Hz/PF --- kWH/Hour

The relation of Volt-Amp-Watt-VA-PF are

1. VA = Volts x Amps
2. Watt =  Volt-amps x Power factor  (OR W = VA x PF)

For example, if the apparent power is 3000 VA and the power factor is 0.8, the real power is 3000x0.8=2400 Watt.

From the Pepco company, my bill is $530.40 (total usage is 4097 KWh) from 11/27/2014 to 12/16/2014.

Delivery Charges:
=================
Distribution services:
Customer charge:                           = 7.39
Energy charge, first 800 KWH x 0.0272      = 21.76
Energe Charge, next 3297 Kwh x 0.0272       = 89.71
Franchise tax (delivery) at .00062 per kWH = 2.54
Universal service charge                     0.36
MD Environmental surchage .00015 per kWH   = 0.61
EmPower MD charge res .0037 per kWh        = 15.16
Gross Receipts tax  2.0408%                = 2.81
Montgomery city energy tax res .01131 per kWH = 46.34
Administrativ credit res .0002912 per kWH  = 1.19-
==========================================================
Subtotal                                      = 185.74 

Supply charges:
===============
Generation services:
  Energy Charge  4097 kwh x 0.07732          = 316.78
  Procumental cost adj res .0005936 per kwh  = 2.43-
Transmission services:
  Energy charge  4097 kwh x .007250         = 29.70
 gross receipts tax at 2.0408%               = 0.61
==========================================================
Subtotal                                     = 344.66
Total                                        = 530.40

So it looks like the charge per kWH is about .0272 + .0037 + .01131 + .07732 + .00725 = 0.12678.

On my home server (idle most of time) with a cpu of AMD Phenom(tm) II X6 1055T Processor, it consumes 1.75kWh in 24 hours. Instantly Kill-a-watt shows 70+ Watt from the machine which makes sense (24 * 70 ~ 1750). So the yearly cost of leaving the machine on is about 1.75 * 365 * 0.12678 = 81.

See http://www.howtogeek.com/234222/why-you-never-need-to-put-your-apple-tv-or-other-modern-devices-to-sleep/ for explanation about Apple TV and Fire TV case. For example, 2.1 watts of power /1000 * 24 * 365 * $0.125 = $2.29 per year.

Laser Engraving Machine

• NEJE 300mW Mini DIY Laser Engraving Machine Picture Logo CNC Laser Printer and 500mW version.
• mdrawBot and 500mW laser engraver
• Laser cube 2.0 (100mw laser diodes). Laser engraver from makeblock.cc (500mw laser engraver).

Kobo ereader & KOReader

I have a Kobo Aura HD. The touch screen is controlled by infrared (like the Nook Simple Touch, no requiring electrical conductivity), not capacitive or resistive technologies. Even a paper or an eraser works on the touch screen. Its screen is 6.8 inch, 1440 x 1080-pixel display with 265 dpi. The brightness is 326 lux. The built-in front light comes the light technology from the ComfortLight. It directs light at the page and boasts an even distribution across the display. The microSD slot can add up to 32GB to the built-in 4GB of storage. The exact model is not on sale now because it is replaced by H2O.

However, the pdf program is not quite useful for scientific papers.

Alternatively, we can try KOReader. Currently my Kobo FW is 3.18.0 (9/23/2015). I am following the procedures on KOReader's Kobo devices page.

1. Go to here and download <KBStartMenu_07inclUp4.zip>. Extract the folder kbmenupngs (it contains png files) and put it to the root folder of Kobo. Also put KoboRoot.tgz to .kobo hidden directory (putting it onto .adds won't work). Reject and reboot.
2. Download <koreader-kobo-arm-linux-gnueabihf-v2014.04> from v2014.04-stable github page. Put koreader folder in the .kobo hidden directory. Ignore the png file and KoboRoot.tgz file there. Reject and reboot.

If something goes wrong, we can go to Settings -> Device information -> Factory reset to reset the system. It can also download the update after the wifi configuration is set up.

When you update koreader, it should be sufficient to extract the koreader folder, without KoboRoot.tgz - that one is needed to add the launcher.

Standby does not work out of box. See http://www.mobileread.com/forums/showthread.php?t=216960&page=85. That is, run

nano -c /media/brb/KOBOeReader/.kobo/koreader/frontend/ui/uimanager.lua

and change the Standby value from 1 to 4 and suspend function call from 0.5 to 2. The standby problem is resolved.

Battery always 100% (too good to be true, I have not used the ereader for a while). http://www.mobileread.com/forums/showthread.php?t=220912. It`ll take care of itself after a few charge cycles.

.kobo folder after reset

After I run factory reset on the device (and plug in it to my computer), I see the device only has 3 hidden directories

brb@brb-P45T-A:~$ ls -la /media/brb/KOBOeReader/
total 20
drwx------  5 brb brb  4096 Dec 31  1969 .
drwxr-x---+ 4 brb root 4096 Oct 11 10:22 ..
drwx------  2 brb brb  4096 Oct 11  2015 .adobe-digital-editions
drwx------  7 brb brb  4096 Oct 11  2015 .kobo
drwx------  8 brb brb  4096 Oct 11  2015 .kobo-images
brb@brb-P45T-A:~$ ls -la /media/brb/KOBOeReader/.kobo
total 152
drwx------ 7 brb brb   4096 Oct 11  2015 .
drwx------ 5 brb brb   4096 Dec 31  1969 ..
-rw-r--r-- 1 brb brb     25 Oct 11  2015 affiliate.conf
drwx------ 2 brb brb   4096 Oct 11  2015 certificates
-rw-r--r-- 1 brb brb     76 Oct 11  2015 device.salt.conf
drwx------ 2 brb brb   4096 Oct 11  2015 dict
drwx------ 2 brb brb   4096 Oct 11  2015 kepub
drwx------ 2 brb brb   4096 Oct 11  2015 Kobo
-rw-r--r-- 1 brb brb 110592 Oct 11  2015 KoboReader.sqlite
drwx------ 6 brb brb   4096 Feb 28  2013 slideshow
-rw-r--r-- 1 brb brb   3298 Oct 11  2015 Trolltech.conf
-rw-r--r-- 1 brb brb     84 Oct 11  2015 version
brb@brb-P45T-A:~$ ls -la /media/brb/KOBOeReader/.kobo-images/
total 32
drwx------ 8 brb brb 4096 Oct 11  2015 .
drwx------ 5 brb brb 4096 Dec 31  1969 ..
drwx------ 3 brb brb 4096 Oct 11  2015 132
drwx------ 3 brb brb 4096 Oct 11  2015 18
drwx------ 3 brb brb 4096 Oct 11  2015 213
drwx------ 3 brb brb 4096 Oct 11  2015 233
drwx------ 3 brb brb 4096 Oct 11  2015 66
drwx------ 3 brb brb 4096 Oct 11  2015 70

Dictionaries

KOReader supports any Stardict format dictionaries. To use that, we need to download and put the dictionary 'folder' in the right place (.kobo/koreader/data/dict) of the Kobo ereader.

I tried two dictionaries (Longman Dictionary of Contemporary English and cdict-big5 dictionary) from http://abloz.com/huzheng/stardict-dic/. And they work fine.

Flexible E-ink

http://liliputing.com/2015/10/wove-band-smartwatch-has-flexible-e-ink-touch-display.html

Trendent USB to ethernet adapter

ASIX AX88772A. The windows driver can be found on axix.com.tw. The one from Trendent website does not work.

How to park your car on a hill

https://www.reddit.com/r/lifehacks/comments/1c6jfb/when_parking_your_car_on_a_hill_put_the_car_in/

When parking your car on a hill, put the car in neutral, set the emergency brake, then put the car in park (or in gear). This puts the weight of the car on the emergency brake rather than the transmission and can extend the life of your transmission.