Friday, November 27, 2009

Automated Home Security System


Automated Home Security system is PIC16F877 based security system with following core features,

  • Support automatic phone dialing using DTMF tones
  • Support inputs from three optical sensors
  • Control external device(s)
  • Built-in alarm with external audio output
  • Allow total customization to the end-users (such as program phone numbers, setup device control sequence, etc) without changing the source code.
  • Password protected system setup

In this design we use PIC16F877 8bit microcontroller as main system controller, NE556 dual timer as an alarm system and 7805 as power regulator. To miniaturize the final product we use some amount of surface mounted parts with this design. Application program(s) of PIC microcontroller is developed using C programming language and release under the terms and conditions of GNU General Public License.

In this design we use some special electronic components/modules which include LCD display module, 4x4 keyboard matrix, telephone isolation transformer, etc. At the time of circuit design we choose common, locally available parts for this design, which include,

  • HD44780 compatible LCD module
  • Custom made 4x4 Key Matrix
  • General 600Ω telephone isolation transformer
  • NTE-R22 3V relay

In this design we use PIC16F877 MCU to generate DTMF tones (with help of R-2R ladder circuit), as a LCD driver and as a general I/O controller. In PCB design we use generally available DIP version of PIC16F877. Except PIC16F877 and BC140, all other semiconductors are in surface mounted packages.

When installing the system (which means in a practical environment) it is recommended to use LASER pointer as a light source. During our field tests we get successful results with the 5mW LASER module.

In this project all the PCB patterns are design using EAGLE layout designer and all the source, component libraries and output files are available to download with the supplied package.

To get the complete project details (including schematic, PCB design and firmware source code and binaries) visit our project repository at http://elect.wikispaces.com

Tuesday, November 17, 2009

20W Hi-Fi Audio Power Amplifier

TDA2030 is most popular, high quality - low cost audio power amplifier and successive version of TDA2006. Typically TDA2030 deliver 14W in 24V with 4Ω output load and 8W in 8Ω output load. Because of it’s wider power bandwidth (10Hz to 140 kHz) and extremely small amount of distortion (0.1% - 0.5%), TDA2030 deliver excellent sound quality with higher performance. In this project we design basic version of TDA2030 mono power amplifier for general use and its design to work with 9V – 24V (500mA) Power Supply Unit.


When building the circuit it is recommended to use PCB design and its important to attach suitable heat-sink to the TDA2030. In this design it is not necessary to have electrical isolation between the IC and the heat-sink.

To get the complete circuit diagrams and PCB designs (Eagle) please check the http://elect.wikispaces.com.