Here is a collection of electronic projects  I found on internet. Many of them only contain circuit or schematic, but several are completed projects, including detailed comment, PCB file and even photos. 

The projects listed here are belong to other persons. I just collect and arrange them in my place. Credit for him/her who builds and publishes the projects. Please also notice what the owners say about copyright stuff in their pages.

I noticed that some of the hosting servers linked is not very stable. If you find broken link, please let me know, by dropping a comment.

The Index:

• Radio Frequency (RF) Circuits [7] :
  1
  2
  3
  4
  5
  6
  7
• Television and Video Projects [2] :
  1
  2
• Computer (PC) Interfacing Projects [3] :
  1
  2
  3
• Power Supply Circuits [5] :
  1
  2
  3
  4
  5
• Telephone and Intercom Circuits [2] :
  1
  2
• Filter Circuits [1] :
  1
• Measurement and Testing Circuits [4] :
  1
  2
  3
  4
• Solar Power Circuits [1]:
  1
• Remote Control (RC) Circuits [2] :
  1
  2
• Timer and Oscillator Circuits [3] :
  1
  2
  3
• Motor Control Circuits [2] :
  1
  2
• Health and Medical Electronic Circuits [2] :
  1
  2
• InfraRed and IrDA Circuits [2] :
  1
  2
• Games and Fun Circuits [2] :
  1
  2
• Security and Alarm Circuits [2] :
  1
  2
• Automotive (Car and Motorcycle) Electronics [2] :
  1
  2
• Laser Circuits [2] :
  1
  2
• Lightning and LEDs Circuits [4] :
  1
  2
  3
  4

—

Sources of the links:

• www.circuits-city.com
• aaroncake.net
• ee.washington.edu
• www.web-ee.com
• www.electronics-lab.com
• and… lot of individual project sites.