Category Archives: Tips

Change default Backup folder of iTunes in Windows 7/8/10

Change default Backup folder of iTunes in Windows 7/8/10:

  • Delete all backup file at C:\Users\___XXXUserNameXXX___\AppData\Roaming\Apple Computer\MobileSync\Backup
  • Delete Backup folder at C:\Users\___XXXUserNameXXX___\AppData\Roaming\Apple Computer\MobileSync\
  • Create a new backup folder: (e.g. D:\RunApp\iTunes\MobileSync\Backup)
  • Run cmd (command promt)
  • Create/Link current iTunes backup folder to the newly created folder by running the below command:
  • mklink /J “C:\Users\___XXXUserNameXXX___\AppData\Roaming\Apple Computer\MobileSync\Backup” “D:\RunApp\iTunes\MobileSync\Backup”
  • Now all backup files will be save into D:\RunApp\iTunes\MobileSync\Backup

How to check Bitcoind block chain download progress level

After install Bitcoin Core in Ubuntu server, run $ bitcoind – daemon to start bitcoin node. It will download all bitcoin blocks to the local server.

  • To check the block download progress, use the below command to see the number of block that has already been downloaded.

$ bitcoin-cli getblockcount

  • Then open the below website to see the current total amount of blocks on public block chain browsers:

  • Compare 2 numbers to calculate downloading progress.

Using Lightning-to-USB-Adapter to copy photo from USB drive to iPhone/iPad


Using Lightning-To-USB Adapter to copy images from USB Flash Drive to iPhone/iPad:

  • Requirement:
    • All image files need to put in a folder name: DCIM
    • Image files must have a filename with exactly 8 characters long (no spaces) plus the file extension (i.e.,; DSCN0164.jpg).
  • How to copy file:
    • If connected iPhone/iPad sees the flash drive, it’ll open all photos in thumbnails. You cannot view more than thumbnails off the drive. To see them bigger, you must import them.
    • Select to import few photo or import all photos.
    • Once you import, pay attention to the dialogue boxes because it’ll offer to delete the photos from the flash drive for you.
    • (You can not export photo from iPhone to flash drive).


Service Registration and Cancellation via SMS for Mobile Phone Service in Vietnam

Service Registration and Cancellation via SMS for Mobile Phone Service in Vietnam (Đăng ký hoặc hủy các dịch vụ giá trị gia tăng của điện thoại đi động bằng SMS):

1. Viettel (Customer Service Operator: 1800-8098)

  • Check currently register services (kiểm tra các dịch vụ mất tiền đang đăng ký): 
    • Viettel: SMS “TC” send to 1228
  • 1.2. Roaming (chuyển vùng quốc tế):
    • Register: sms “CVQT” send to 138
    • Cancel roaming: sms “HUY” send to 138  (when receiving confirmation sms, send “DONG Y”).
  • International call (gọi quốc tế):
    • Register: sms “QT ON” send to 133
    • Cancel service: sms “QT OFF” send to 133
  • Miss-call Alert MCA service (Thông báo có cuộc gọi nhỡ):
    • Register basic package: sms “DKC” send to 193
    • Register advanced package: sms “DK” send to 193
    • Cancel service: sms “HUY” send to 193
  • Data service package (3G service – dịch vụ 3G): 
    • Mobile Internet 3G charge: 

Package Name

Subscription   (d/month)

Free usage limit

Limit before changing speed

Fee for exceeded usage



















Unlimited (Không giới hạn)

600MB/month (tháng)




Không giới hạn





Không giới hạn



 (Effective on 16/10/2013)

2. Vinaphone:

  • Check currently register services (kiểm tra các dịch vụ mất tiền đang đăng ký): 
    • Vinaphone: SMS “TK” send to 123

3. Mobifone:

  • Check currently register services (kiểm tra các dịch vụ mất tiền đang đăng ký): 
    • Mobifone: SMS “KT” send to 994

Install Mac OS X 10.11 (El Capitan) and xCode on VirtualBox


  • VirtualBox:
  • Download Mac OS X El Capitan 10.11 via torrent
  • Download xCode from AppStore (inside virtual Mac OS)
  • GPX File editor: Adze Lite (for Mac OS) (download from AppStore)




Chọn kính thiên văn khúc xạ hay phản xạ?

Câu hỏi chọn kính thiên văn khúc xạ hay phản xạ thực chất là câu hỏi: ” Chọn thấu kính hay gương ? “

Đây là câu hỏi rất nhiều bạn thắc mắc khi có ý định mua hoặc tự làm một chiếc kính để phục vụ quan sát, thỏa mãn niềm đam mê của mình.

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